LIBRARY 

OF  THE 

University  of  California. 

Mrs.  SARAH  P.  WALSWORTH. 

Received  October,  i8g4. 
z/lccessions  No.  SJ/^^^^.     Class  No.; 


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ELEMENTS 


OF 


AGRICULTURAL  CHEMISTRY. 


IN 


A  COURSE  OF  LECTURES 

FOR 

THE  BOARD  OF  AGRICULTURE 


BY  SIR  HUMPHRY  DAVY,  LL.  D. 
F.  R.  S.  L.  &  E.  M.  R.  I. 

Member  of  the  Boar  J  of  Agriculture,  of  the  Royal  Irish  Academy,  of  the 

Academies  of  St.  Petersburgh,  Stochholm,  Berlin,  Philadelphia,  8cc, 

and  Honorary  Professor  oi  Chemistry  to  the  Royal  Institution. 


PUBLISHED 

By  Eastbum,  Kirk  &  Co.  New-York ;  and  Ward  &  Lilly,  Boston 

1815. 


S^^ifCf. 


TO   THE 

PRESIDENT  AND  MEMBERS 

OF 

THE  BOARD  OF  AGRICULTURE 

FOR  THE  YEAR  1812. 

THESE    LECTURES, 

PUBLISHED  AT  THEIR  REQUEST, 

ARE  INSCRIBED^ 
A3  A  TESTIMONY  OF  THE  RESPECT  OF  THE   AUTHOB, 


ai3  GRATITUDE  FOR  THE   ATTENTION  WITH   WHICH 
THEY    HAVE   BEEN   RECEIVED. 


ADVERTISEMENT. 


DURING  ten  years,  since  1802, 1  have  had  the 
honour,  every  Session,  of  delivering  Courses  of  Lec« 
tures  before  the  Board  of  Agriculture.  I  have  endea- 
voured, at  all  times,  to  follow  in  them  the  progress  of 
chemical  discovery  ;  they  have  therefore  varied  every 
year  :  and  such  is  the  rapidity  with  which  Chemistry 
is  extending,  that  some  alterations  and  improvements 
were  rendered  necessary  at  the  time  they  were  prepar- 
ing for  the  press. 

The  Duke  of  Bedford  has  enabled  me  to  stamp  a 
value  upon  this  work,  by  permitting  me  to  add  to  it  the 
results  of  the  experiments  instituted  by  His  Grace 
upon  the  quantity  of  produce  afforded  by  the  different 
grasses. 

I  am  indebted  for  much  useful  information  to 
many  members  of  the  Board ;  of  which  acknowledg- 
ments will  be  found  in  the  body  of  the  work.  If  there 
are  any  omisssions  on  this  head,  I  trust  they  will  be 
attributed  to  defect  of  recollection,  and  not  to  any 
want  of  candour  or  of  gratitude. 

Where  I  have  derived  any  specific  statements  from 
books,  I  have  always  quoted  the  authors ;  but  I  have 


VI  ADVERTISEMENT. 

not  always  made  references  to  such  doctrines  as  are 
become  current,  the  authors  of  which  are  well  known  j 
and  which  may  be  almost  considered  as  the  property 
of  all  enlightened  minds. 

Amongst  books  to  which  I  have  not  referred  for 
any  particular  facts,  but  which  contain  much  useful 
general  information,  I  shall  mention  the  Earl  of  Dun- 
donald's  Treatise  on  the  connection  of  Chemistry  with 
Agriculture ;  Mr.  Rennie's  Dissertations  on  Peat ;  and 
the  General  Report  of  the  Agriculture  of  Scotland. 
This  last  work  did  not  come  into  my  hands  till  the 
concluding  sheets  of  these  Lectures  were  printing. 
Had  it  been  in  circulation  before,  I  should  have  profit- 
ed by  many  statements  given  in  it,  particularly  those 
of  the  opinions  of  the  enlightened  Professor  of  Agri- 
culture  in  the  University  of  Edinburgh;  and  I  should 
have  dwelt  with  satisfaction  on  the  importance  given 
to  some  chemical  doctrines  by  his  experience. 


Berkeley  Square^ 
Marchy2l  1813. 


CONTENTS. 


LECTURE  I.  page. 

Introduction.   General  Views  of  the  Objects  of  the  course, 
and  of  the  order  in  which  they  are  to  be  discussed  S 

LECTURE  II. 
Of  the  general  Powers  of  Matter  which  influence  Vegeta- 
tion ;  of  Gravitation,  of  Cohesion,  of  Chemical  Attrac- 
tion, of  Heat,  of  Light,  of  Electricity,  ponderable  Sub- 
stances, Elements  of  Matter,  particularly  those  found  in 
Vegetables,  Laws  of  their  Combinations  and  Arrange- 
ments     -28 

LECTURE  in. 
On  the  Organization  of  Plants.  Of  the  Roots,  Trunk,  and 
Branches  ;  of  their  Structure.  Of  the  Epidermis.  Of 
the  cortical,  and  albumous  Parts  of  Leaves,  Flowers,  and 
Seeds.  Of  the  Chemical  Constitution  of  the  Organs  of 
Plants,  and  the  Substances  found  in  them.  Of  mucila- 
ginous, saccharine,  extractive,  resinous,  and  oily  Sub- 
stances, and  other  vegetable  Compounds,  their  Ar- 
rangements in  the  organs  of  Plants,  their  Composition, 
Changes,  and  Uses       -  .        -        .        „        ,        50 

LECTURE  IV. 
On  Soils :  their  constituent  Parts.    On  the  Analysis  of 
Soils.     Of  the  Uses  of  the  Soil.     Of  the  Rocks  and 
Strata  found  beneath  Soils.    Of  the  Improvement  of 
Soils.    ---- 130 

LECTURE  V. 

On  the  Nature  and  Constitution  of  the  Atmosphere,  and 
its  influence  on  Vegetables.    Of  the  Germinatiom  of 


Vm  CONTENTS. 

Seeds.  Of  the  Functions  of  Plants  in  their  different 
Stages  of  Growth  ;  with  a  general  view  of  the  progress 
of  Vegetation 18: 

LECTURE  Vr. 
Of  Manures  of  vegetable  and  animal  Origin.  Of  the  man- 
ner in  which  they  become  the  Nourishment  of  the  Plant. 
Of  Fermentation  and  Putrefaction.  Of  the  different 
Species  of  Manures  of  vegetable  Origin  ;  of  the  differ- 
ent Species  of  animal  Origin.  Of  mixed  manures. 
General  Principles  with  respect  to  the  use  and  applica- 
tion of  such  Manures 239 

LECTUPvE  VIL 
On  Manures  of  mineral  Origin,  or  fossilc  Manures  ;  their 
Preparation,  and  the  Manner  in  which  they  act.  Of 
Lime  ia  its  different  States  ;  Operation  of  Lime  as  a 
Manure  and  a  cement ;  different  combinations  of  Lime. 
Of  Gypsum;  Ideas  respecting  its  use.  Of  other  Neu- 
tro-saline  Compounds,  employed  as  Manures.  Of  Al- 
kalies and  alkaline  Salts  ;  of  common  Salt         •         -       276 

LECTURE  VIH. 
On  the  improvement  of  Lands  by  Burning ;  chemical 
Principles  of  this  Operation.  On  Irrigation  and  its  ef- 
fects. On  Fallowing  ;  its  disadvantages  and  uses.  On 
the  convertible  Husbandry  founded  on  regular  rotations 
of  different  Crops.  On  Pasture-  On  various  Agricul- 
tural Objects  connected  with  Chemistry.     Conclusion     SOT 

APPENDIX. 
An  account  of  the  Results  of  Experimejits  on  the  Produce 
and  Nutritive  Qualities  of  different  Grasses,   and  other 
Plants,  used  as  the  Food  of  Animals. 


COURSE  OF  LECTURES 


OS 


THE  ELEMENTS 


OE 


AGRICULTURAL  CHEMISTBT. 


A 

COURSE  OF  LECTURES,  &e. 


LECTURE   I. 

Introduction.     General  Views  of  the  Objects  of  the  Course^ 
and  of  the  order  in  which  they  are  to  be  discussed. 

It  is  with  great  pleasure  that  I  receive  the  permis- 
sion to  address  so  distinguished  and  enlightened  an 
Audience  on  the  subject  of  Agricultural  Chemistry. 

That  any  thing  which  I  am  able  to  bring  forward, 
should  be  thought  worthy  the  attention  of  the  Board 
of  Agriculture,  I  consider  as  an  honour;  and  I  shall 
endeavour  to  prove  my  gratitude,  by  employing  every 
exertion  to  illustrate  this  department  of  knowledge, 
and  to  point  out  its  uses. 

In  attempting  these  objects,  the  peculiar  state  of 
the  enquiry  presents  many  difficulties  to  a  Lecturer. 
Agricultural  Chemistry  has  not  yet  received  a  regular 
and  systematic  form.  It  has  been  pursued  by  compe- 
tent experimenters  for  a  short  time  only;  the  doctrines 
have  not  as  yet  been  collected  into  any  elementary  trea- 
tise; and  on  an  occasion  when  I  am  obliged  ,to  trust 
so  much  to  my  own  arrangements,  and  to  my  own 


C      4      ] 

limited  information,  I  cannot  but  feel  difEdent  as  to 
the  interest  that  may  be  excited,  and  doubtful  of  the 
success  of  the  undertaking.  I  know,  however,  that 
your  candour  will  induce  you  not  to  expect  any  thing 
like  a  finished  work  upon  a  science  as  yet  in  its  infancy; 
and  I  am  sure  you  will  receive  with  indulgence  the 
first  attempt  made  to  illustrate  it,  in  a  distinct  course 
of  public  lectures. 

Agricultural  Chemistry  has  for  its  objects  all 
those  changes  in  the  arrangements  of  matter  connect- 
ed with  the  growth  and  nourishment  of  plants ;  the 
comparative  values  of  their  produce  as  food;  the  con- 
stitution of  soils;  the  manner  in  which  lands  are  en- 
riched by  manure,  or  rendered  fertile  by  the  different 
processes  of  cultivation.  Enquiries  of  such  a  nature 
cannot  but  be  interesting  and  important,  both  to  the 
theoretical  agriculturist,  and  to  the  practical  farmer. 
To  the  first,  they  are  necessary  in  supplying  most  of 
the  fundamental  principles  on  which  the  theory  of  the 
art  depends.  To  the  second,  they  are  useful  in  afford- 
ing simple  and  easy  experiments  for  directing  his  la- 
bours, and  for  enabling  him  to  pursue  a  certain  and 
systematic  plan  of  improvement. 

It  is  scarcely  possible  to  enter  upon  any  investiga- 
tion in  agriculture  without  finding  it  connected,  more 
or  less,  with  doctrines  or  elucidations  derived  from 
chemistry. 

If  land  be  unproductive,  and  a  system  of  ameliorat- 
ing it  is  to  be  attempted,  the  sure  method  of  obtaining 
the  object  is  by  determining  the  cause  of  its  sterility, 
which  must  necessarily  depend  upon  some  defect  in 


[        5        3 

the  constitution  of  the  soil,  which  may  be  easily  disi 
covered  by  chemical  analysis. 

Some  lands  of  good  apparent  texture  are  yet 
sterile  in  a  high  degree;  and  common  observation  and 
common  practice  afford  no  means  of  ascertaining  the 
cause,  or  of  removing  the  effect.  The  application  of 
chemical  tests  in  such  cases  is  obvious ;  for  the  soil 
must  contain  some  noxious  principle  which  may  be 
easily  discovered,  and  probably  easily  destroyed. 

Are  any  of  the  salts  of  iron  present?  ihey  may  be 
decomposed  by  lime.  Is  there  an  excess  of  siliceous 
sand  ?  the  system  of  improvement  must  depend  on 
the  application  of  clay  and  calcareous  matter.  Is 
ther*e  a  defect  of  calcareous  matter?  the  remedy  is 
obvious.  Is  an  excess  of  vegetable  matter  indicated  ? 
it  may  be  removed  by  liming,  paring,  and  burning. 
Is  there  a  deficiency  of  vegetable  matter  ?  it  is  to  be 
supplied  by  manure. 

A  question  concerning  the  different  kinds  of  lime- 
stone to  be  employed  in  cultivation  often  occurs.  To 
determine  this  fully  in  the  common  way  of  experience, 
would  demand  a  considerable  time,  perhaps  some 
years,  and  trials  which  might  be  injurious  to  crops ; 
but  by  simple  chemical  tests  the  nature  of  a  limestone 
is  discovered  in  a  few  minutes  ;  and  the  fitness  of  its 
application,  whether  as  a  manure  for  different  soils,  or 
as  a  cement,  determined. 

Peat  earth  of  a  certain  consistence  and  composi- 
tion is  an  excellent  manure ;  but  there  are  some  varie- 
ties of  peats  which  contain  so  large  a  quantity  of  fer- 
ruginous matter  as  to  be  absolutely  poisonous  to  plants. 


C         6         ] 

Nothing  can  be  more  simple  than  the  chemical  opera- 
tion for  determining  the  nature,  and  the  probable  uses 
of  a  substance  of  this  kind. 

There  has  been  no  question  on  which  more  dif- 
ference of  opinion  has  existed,  than  that  of  the  state 
in  which  manure  ought  to  be  ploughed  into  the  land  ; 
whether  recent,  or  when  it  has  gone  through  the  pro- 
cess of  fermentation  ?  and  this  question  is  still  a  sub- 
ject of  discussion  ;  but  whoever  will  refer  to  the  sim- 
plest principles  of  chemistry,  cannot  entertain  a  doubt 
on  the  subject.  As  soon  as  dung  begins  to  decom- 
pose, it  throws  off  its  volatile  parts,  which  are  the 
most  valuable  and  most  efficient.  Dung  which  has  fer- 
mented, so  as  to  become  a  mere  soft  cohesive  mass, 
has  generally  lost  from  one  third  to  one  half  of  its 
most  useful  constituent  elements.  It  evidently  should 
be  applied  as  soon  as  fermentation  begins,  that  it  may 
exert  its  full  action  upon  the  plant,  and  lose  none  of 
its  nutritive  powers. 

It  would  be  easy  to  adduce  a  multitude  of  other 
instances  of  the  same  kind  ;  but  sufficient  I  trust  has 
been  said  to  prove,  that  the  connexion  of  Chemistry 
with  Agriculture  is  not  founded  on  mere  vague  specu- 
lation, but  that  it  offers  principles  which  ought  to  be 
understood  and  followed,  and  which  in  their  progres- 
sion and  ultimate  results,  can  hardly  fail  to  be  highly 
beneficial  to  the  community. 

A  view  of  the  objects  in  this  Course  of  Lectures, 
and  of  the  manner  in  which  they  are  to  be  treated, 
will  not,  I  hope,  be  considered  as  an  improper  intro- 
duction.    It  will  inform  you  what  you  are  to  expect ; 


C      7      3 

it  will  afFord  a  general  idea  of  the  connexion  of  the 
different  parts  of  the  subject,  and  of  their  relative  im- 
portance ;  it  will  enable  me  to  give  some  historical 
details  of  the  progress  of  this  branch  of  knowledge, 
and  to  reason  from  what  has  been  ascertained,  con- 
cerning what  remains  to  be  investigated  and  disco- 
vered. 

The  phenomena  of  vegetation  must  be  consider- 
ed as  an  important  branch  of  the  science  of  organized 
nature  ;  but  though  exalted  above  inorganic  matter, 
vegetables  are  yet  in  a  great  measure  dependent  for 
their  existence  upon  its  laws.  They  receive  their  nour- 
ishment from  the  external  elements ;  they  assimilate 
it  by  means  of  peculiar  organs  ;  and  it  is  by  examin- 
ing their  physical  and  chemical  constitution,  and  the 
substances  and  powers  which  act  upon  them,  and  the 
modifications  which  they  undergo,  that  the  scientific 
principles  of  Agricultural  Chemistry  are  obtained. 

According  to  these  ideas,  it  is  evident  that  the 
study  ought  to  be  commenced  by  some  general  en- 
quiries into  the  composition  and  nature  of  material 
bodies,  and  the  laws  of  their  changes.  The  surface 
of  the  earth,  the  atmosphere,  and  the  water  deposited 
from  it,  must  either  together  or  separately  afFord  all  the 
principles  concerned  in  vegetation ;  and  it  is  only  by 
examining  the  chemical  nature  of  these  principles, 
that  we  are  capable  of  discovering  what  is  the  food  of 
plants,  and  the  manner  in  which  this  food  is  supplied 
and  prepared  for  their  nourishment.  The  principles 
of  the  constitution  of  bodies,  consequently,  will  form 
the  first  subject  for  our  consideration. 


I  8  1 

By  methods  of  analysis  dependent  upon  chemi- 
cal and  electrical  instruments  discovered  in  late  times, 
it  has  been  ascertained  that  all  the  varieties  of  material 
substances  may  be  resolved  into  a  comparatively  small 
number  of  bodies,  which,  as  they  are  not  capable  of 
being  decompounded,  are  considered  in  the  present 
state  of  chemical  knowledge  as  elements.    The  bodies 
incapable  of  decomposition  at  present  known  are  forty- 
seven.     Of  these,  thirty-eight  are  metals  ;  seven  are 
inflammable  bodies  ;  and  two  are  gasses  which  unite 
with  metals  and  inflammable  bodies,  and  form  with 
them  acids,  alkalies,  earths,  or  other  analogous  com- 
pounds.    The  chemical  elements  acted  upon  by  at- 
tractive powers  combine  in  different  aggregates.     In 
their  simpler  combinations,  they  produce  various  crys- 
talline substances,  distinguished  by  the  regularity  of 
their  forms.    In  more  complicated  arrangements,  they 
constitute  the  varieties  of  vegetable  and  animal  sub- 
stances, bear  the  higher  character  of  organization, 
and  are  rendered  subservient  to  the  purposes  of  life. 
And  by  the  influence  of  heat,  light,    and  electrical 
powers^  there  is  a  constant  series  of  changes ;  matter 
assumes  new  forms,  the  destruction  of  one  order  of 
beings  tends  to  the  conservation  of  another,  solution 
and  consolidation,  decay  and  renovation,  are  connect- 
ed, and  whilst  the  parts  of  the  system  continue  in 
a  state  of  fluctuation  and  change,  the  order  and  har- 
mony of  the  whole  remain  unalterable. 

After  a  general  view  has  been  taken  of  the  na- 
ture of  the  elements,  and  of  the  principles  of  chemi- 
cal changes,  the  next  object  will  be  the  structure  and 


[93 

constitution  of  plants.  In  all  plants  there  exists  a 
system  of  tubes  or  vessels,  which  in  one  extremity 
terminate  in  the  roots,  and  at  the  other  in  leaves.  It 
is  by  the  capillary  action  of  the  roots  that  fluid  mat- 
ter is  taken  up  from  the  soil.  The  sap  in  passing  up- 
wards becomes  denser,  and  more  fitted  to  deposit 
solid  matter  ;  it  is  modified  by  exposure  to  heat,  light, 
and  air  in  the  leaves  ;  descends  through  the  bark, 
in  its  progress  ^  produces  new  organized  matter  ;  and 
is  thus  in  its  vernal  and  autumnal  flow,  the  cause  of 
the  fermentation  of  new  parts,  and  of  the  more  per- 
fect evolution  of  parts  already  formed. 

In  this  part  ctf"  the  enquiry  I  shall  endeavour  to 
connect  together  into  a  general  view,  the  observations 
of  the  most  enlighted  philosophers  who  have  studied 
the  physiology  of  vegetation.  Those  of  Grew,  Mal- 
pighi,  Sennebier,  Darwin,  and,  above  all,  of  Mr. 
Knight.  He  is  the  latest  enquirer  into  these  interest- 
ing subjects,  and  his  labours  have  tended  most  to  il- 
lustrate this  part  of  the  economy  of  nature. 

The  chemical  composition  of  plants  has  within 
the  last  ten  years,  been  elucidated  by  the  experiments 
of  a  number  of  chemical  philosophers,  both  in  this, 
and  in  other  countries  ;  and  it  forms  a  beautiful  part  of 
general  chemistry  ;  it  is  too  extensive  to  be  treated  of 
minutely  ;  but  it  will  be  necessary  to  dwell  upon 
such  parts  of  it,  as  afford  practical  inferences. 

If  the  organs  of  plants  be  submitted  to  chemical 
analysis,  it  is  found  that  their  almost  infinite  diversity 
of  form,  depends  upon  different  arrangements  and 
combinations  of  a  very  few  of  the  elements  j  seldom 


C       10      ] 

more  than  seven  or  eighr  belong  to  them,  and  three  con- 
stitute the  greatest  part  of  their  organized  matter  ;  and 
according  to  the  manner  in  which  these  elements  are 
disposed,  arise  the  diflerent  properties  of  the  products 
of  vegetation,  whether  employed  as  food,  or  for  other 
purposes  and  wants  of  life. 

The  value  and  uses  of  every  species  of  agricul- 
tural produce,  are  most  correctly  estimated  and  applied 
when  practical  knowledge  is  assisted  by  principles  de- 
rived from  chemistry.  The  compounds  in  vegetables 
really  nutritive  as  the  food  of  animals,  are  very  few  ; 
farina  or  the  pure  matter  of  starch,  gluten,  vegetable 
jellv,  and  extract.  Of  these  the  most  nutritive  is 
gluten,  which  approaches  nearest  in  its  nature  to  ani- 
mal matter,  and  which  is  the  substance  that  gives  to 
wheat  its  superiority  over  other  grain.  The  next  in 
order  as  to  nourishing  power,  is  sugar,  then  farina  ; 
and  last  of  all  gelatinous  and  extractive  matters.  Sim- 
ple tests  of  the  relative  nourishing  powers  of  the  differ- 
ent species  of  food,  are  the  relative  quantities  of  these 
substances  that  they  afford  by  analysis  ;  and  though 
taste  and  appearance  must  influence  the  consumption 
of  all  articles  in  years  of  plenty,  yet  they  are  less  at- 
tended to  in  times  of  scarcity,  and  on  such  occasions 
this  kind  of  knowledge  may  be  of  the  greatest  impor- 
tance. Sugar  and  farina  or  starch,  are  very  similar 
in  composition,  and  are  capable  of  being  converted 
into  each  other  by  simple  chemical  processes.  In  the 
discussion  of  their  relations,  I  shall  detail  to  you  the 
results  ot  some  recent  experiments  which  will  be 
found  possessed  of  applications  both  to  the  oeconomy 


L      11      ] 

of  vegetation,  and  to  some  important  processes  of; 
manufacture. 

All  the  varieties  of  substances  found  in  plants, 
are  produced  from  the  sap,  and  the  sap  of  plants  is 
derived  from  water,  or  from  the  fluids  in  the  soil,  and 
it  is  altered  by,  or  combined  with  principles  derived 
from  the  atmosphere.  The  influence  of  the  soil,  of 
water,  and  of  air,  will  therefore  be  the  next  subject  of, 
consideration.  Soils  in  all  cases  consist  of  a  mixture 
of  different  finely  divided  earthy  matters  ;  with  ani- 
mal or  vegetable  substances  in  a  state  of  decomposi- 
tion, and  certain  saline  ingredients.  The  earthy  mat- 
ters are  the  true  basis  of  the  soil ;  the  other  parts, 
whether  natural,  or  artificially  introduced,  operate  in 
the  same  manner  as  manures.  Four  earths  generally 
abound  in  soils,  the  aluminous,  the  siliceous,  the  cal- 
careous, and  the  magnesian.  These  earths,  as  I  have 
discovered,  consist  of  highly  inflammable  metals 
united  to  pure  air  or  oxygene ;  and  they  are  not,  as 
far  as  we  know,  decomposed  or  altered  in  vegetation. 
The  great  use  of  the  soil  is  to  afford  support  to  the 
plant,  to  enable  it  to  fix  its  roots,  and  to  derive  nour- 
ishment by  its  tubes  slowly  and  gradually,  from  the  so- 
luble and  dissolved  substances  mixed  with  the  earths. 
That  a  particular  mixture  of  the  earths  is  con- 
nected with  fertility,  cannot  be  doubted  :  and  almost 
all  sterile  soils  are  capable  of  being  improved,  by  a 
modification  of  their  earthy  constituent  parts.  I  shall 
describe  the  simplest  method  as  yet  discovered  of 
analysing  soils,  and  of  ascertaining  the  constitution 
and  chemical  ingredients  which  appear  to  be  connect- 


C  12  ] 

ed  with  fertility  and  on  this  subject  many  of  the  for- 
mer difficulties  of  investigation  will  be  found  to  be  re- 
moved by  recent  enquiries. 

The  necessity  of  water  to  vegetation,  and  the  lux- 
uriancy  of  the  growth  of  plants  connected  with  the  pre- 
sence of  moisture  in  the  southern  countries  of  the  old 
continent,  led  to  the  opinion  so  prevalent  in  the  early 
schools  of  philosophy,  that  water  was  the  great  pro- 
ductive element,  the  substance  from  which  all  things 
were  capable  of  being  composed,  and  into  which 
they  were  finally  resolved.  The  "  «e'<"o»  /«"  J^^*?"  of 
the  poet,  "  water  is  the  noblest,"  seems  to  have 
been  an  expression  of  this  opinion,  adopted  by  the 
Greeks  from  the  Eg}^ptians,  taught  by  Thales,  and 
revived  by  the  alchemists  in  late  times.  Van  Hel- 
mont  in  1610,  conceived  that  he  had  proved  by  a  de- 
cisive experiment,  that  all  the  products  of  vegetables 
were  capable  of  being  generated  from  water.  His 
results  were  shewn  to  be  fallacious  by  Woodward  in 
1691  ;  but  the  true  use  of  water  in  vegetation  was 
unknown  till  1785  ;  when  Mr.  Cavendish  made  the 
grand  discovery,  that  it  was  composed  of  two  elastic 
fluids  or  gases,  inflammable  gas  or  hydrogene,  and 
vital  gas  or  oxygene. 

Air,  like  water,  was  regarded  as  a  pure  element 
by  most  of  the  ancient  philosophers :  a  few  of  the 
chemical  enquirers  in  the  sixteenth  and  seventeeth 
centuries,  formed  some  happy  conjectures  respecting 
its  real  nature.  Sir  Kenelm  Digby  in  1 660,  supposed 
that  it  contained  some  saline  matter,  which  was  an 
essential  food  of  plants.    Boyle,  Hooke,  and  Mayow, 


[  13  ] 

between  1665  and  1680,  stated  that  a  small  part  of  it 
only  was  consumed  in  the  respiration  of  animals,  and 
in  the  combustion  of  inflammable  bodies  ;  but  the 
true  statical  analysis  of  the  atmosphere  is  comparative- 
ly a  recent  labour,  achieved  towards  the  end  of  the 
last  century  by  Scheele,  Priestley,  and  Lavoisier. 
These  celebrated  men  shewed  that  its  principal 
elements  are  two  gases,  oxygene  and  azote,  of  which 
the  first  is  essential  to  flame,  and  to  the  life  of  animals, 
and  that  it  likewise  contains  small  quantities  of 
aqueous  vapour,  and  of  carbonic  acid  gas  ;  and  La- 
voisier proved  that  this  last  body  is  itself  a  compound 
elastic  fluid,  consisting  of  charcoal  dissolved  in  oxy- 
gene. 

Jethro  Tull,  in  his  treatise  on  Horse-hoeing,  pub- 
lished in  1 733,  advanced  the  opinion  that  minute 
earthy  particles  supplied  the  whole  nourishment  of  the 
vegetable  world  ;  that  air  and  water  were  chiefly  useful 
in  producing  these  particles  from  the  land  ;  and  that 
manures  acted  in  no  other  way  than  in  ameliorating  the 
texture  of  the  soil,  in  short,  that  their  agency  was 
mechanical.  This  ingenious  author  of  the  new  system 
of  agriculture  having  observed  the  excellent  effects 
produced  in  farming  by  a  minute  division  of  the  soil, 
and  the  pulverisation  of  it  by  exposure  to  dew  and  air, 
was  misled  by  carrying  his  principles  too  far.  Duh- 
amel,  in  a  work  printed  in  1 754,  adopted  the  opinion 
of  Tull,  and  stated  that  by  finely  dividing  the  soil,  any 
number  of  crops  might  be  raised  in  succession  from 
the  same  land.  He  attempted  also  to  prove,  by  di- 
rect experiments,  that  vegetables  of  every  kind  were 


[  14  1 

capable  of  being  raised  without  manure.  This  cele- 
brated horticulturist  Hved,  however,  sufficiently  long 
to  alter  his  opinion.  The  results  of  his  later  and 
most  refined  observations  led  him  to  the  conclusion, 
that  no  single  material  afforded  the  food  of  plants. 
The  general  experience  of  farmers  had  long  before 
convinced  the  unprejudiced  of  the  truth  of  the  same 
opinion,  and  that  manures  were  absolutely  consumed 
in  the  process  of  vegetation.  The  exhaustion  of  soils 
by  carrying  off  corn  crops  from  them,  and  the  effects 
of  feeding  cattle  on  lands,  and  of  preserving  their 
manure,  offer  familiar  illustrations  of  the  principle ; 
and  several  philosophical  enquirers,  particularly  Has- 
senfratz  and  Saussure,  have  shewn  by  satisfactory  ex- 
periments, that  animal  and  vegetable  matters  deposit- 
ed in  soils  are  absorbed  by  plants,  and  become  a  part 
of  their  organized  matter.  But  though  neither  water, 
nor  air,  nor  earth,  supplies  the  whole  of  the  food  of 
plants,  yet  they  all  operate  in  the  process  of  vegeta- 
tion. The  soil  is  the  laboratory  in  which  the  food  is 
prepared.  No  manure  can  be  taken  up  by  the  roots 
of  plants  unless  water  is  present ;  and  water  or  its 
elements  exist  in  all  the  products  of  vegetation.  The 
germination  of  seeds  does  not  take  place  without  the 
presence  of  air  or  oxygene  gas  ;  and  in  the  sunshine 
vegetables  decompose  the  carbonic  acid  gas  of  the  at- 
mosphere, the  carbon  of  which  is  absorbed,  and  be- 
comes a  part  of  their  organized  matter,  and  the  oxy- 
gene gas,  the  other  constituent,  is  given  off ;  and  in 
consequence  of  a  variety  of  agencies,  the  cEConomy  of 
vegetaUon  is  made  subservient  to  the  general  order  of 
the  system  of  nature. 


C       15      3 

It  is  shewn  by  various  researches,  that  the  constitu- 
tion of  the  atmosphere  has  been  always  the  same  since 
the  time  that  it  was  first  accurately  analysed  ;  and 
this  must  in  a  great  measure  d&pend  upon  the  powers 
of  plants  to  absorb  or  decompose  the  putrifying  or  de- 
caying remains  of  animals  and  vegetables,  and  the 
gaseous  effluvia  w^hich  they  are  constantly  emitting. 
Carbonic  acid  gas  is  formed  in  a  variety  of  processes 
of  fermentation  and  combustion,  and  in  the  respiration 
of  animals,  and  as  yet  no  other  process  is  known  in 
nature  by  which  it  can  be  consumed,  except  vegeta- 
tion. Animals  produce  a  substance  which  appears  to 
be  a  necessary  food  of  vegetables  ;  vegetables  evolve 
a  principle  necessary  to  the  existence  of  animals  ;  and 
these  different  classes  of  beings  seem  to  be  thus  con- 
nected together  in  the  exercise  of  their  living  functions 
and  to  a  certain  extent  made  to  depend  upon  each 
other  for  their  existence.  Water  is  raised  from  the 
ocean,  diffused  through  the  air,  and  poured  down 
upon  the  soil,  so  as  to  be  applied  to  the  purposes 
of  life.  The  different  parts  of  the  atmosphere  are 
mingled  together  by  winds  or  changes  of  tempera- 
ture, and  successively  brought  in  contact  with  the 
surface  of  the  earth,  so  as  to  exert  their  fertilizing  in- 
fluence. The  modifications  of  the  soil,  and  the  ap- 
plication of  manures  are  placed  within  the  power  of 
man,  as  if  for  the  purpose  of  awakening  his  industry 
and  of  calling  forth  his  powers. 

The  theory  of  the  general  operation  of  the  more 
compound  manures  may  be  rendered  very  obvious  by 
simple  chemical  principles  5    but  there  is  still  much 


t        16        3 

to  be  discovered  with  regard  to  the  best  methods 
of  rendering  animal  and  vegetable  substances  soluble  ; 
with  respect  to  the  processes  of  decomposition,  how 
they  may  be  accelerated  or  retarded,  and  the  means 
of  producing  the  greatest  effects  from  ihe  materials 
employed  :  these  subjects  will  be  attended  to  in  the 
Lecture  on  Manures. 

Plants  are  found  by  analysis  to  consist  princi- 
pally of  charcoal  and  aeriform  matter.  They  give 
out  by  distillation  volatile  compounds,  the  elements 
of  which  are  pure  air,  inflammable  air,  coally  matter, 
and  azote,  or  that  elastic  substance  which  forms  a 
great  part  of  the  atmosphere,  and  which  is  incapable 
of  supporting  combustion.  These  elements  they  gain 
either  by  their  leaves  from  the  air,  or  by  their  roots 
from  the  soil.  All  manures  from  organized  substan- 
ces contain  the  principles  of  vegetable  matter,  which 
during  putrefaction  are  rendered  either  soluble  in 
water  or  aeriform — and  in  these  states  they  are  capa- 
ble of  being  assimilated  to  the  vegetable  organs.  No 
one  principle  affords  the  pabulum  of  vegetable  hfe ; 
it  is  neither  charcoal  nor  hydrogene,  nor  azote  nor 
oxygene  alone ;  but  all  of  them  together  in  various 
states  and  various  combinations.  Organic  substances 
as  soon  as  they  are  deprived  of  vitality,  begin  to  pass 
through  a  series  of  changes  which  end  in  their  com- 
plete destruction,  in  the  entire  separation  and  dissipa- 
tion of  the  parts.  Animal  matters  are  the  soonest  des- 
troyed by  the  operation  of  air,  heat,  and  light.  Vege- 
ble  substances  yield  more  slowly,  but  finally  obey  the 
same  laws.    The  periods  of  the  application  of  manures 


c     17    : 

from  decomposing  animal  and  vegetable  substances 
depend  upon  the  knowledge  of  these  principles,  and 
I  shall  be  able  to  produce  some  new  and  important 
facts  founded  upon  them,  w^hich  I  trust  will  remove 
all  doubt  from  this  part  of  agricultural  theory. 

The  chemistry  of  the  more  simple  manures  ;  the 
manures  which  act  in  very  small  quantities,  such  as 
gypsum,  alkalies,  and  various  saline  substances,  has 
hitherto  been  exceedingly  obscure.  It  has  been  gen- 
erally supposed  that  these  materials  act  in  the  vegetable 
ceconomy  in  the  same  manner  as  condiments  or  stimu- 
lants in  the  animal  ceconomy,  and  that  they  render  the 
common  food  more  nutritive.--  It  seems,  however,  a 
much  more  probable  idea,  that  they  are  actually  a 
part  of  the  true  food  of  plants,  and  that  they  supply 
that  kind  of  matter  to  the  vegetable  fibre,  which  is 
analogous  to  the  bony  matter  in  animal  structures. 

The  operation  of  gypsum,  it  is  well  known,  is 
extremely  capricious  in  this  country,  and  no  certain 
data  have  hitherto  been  offered  for  its  application. 

There  is,  however,  good  ground  for  supposing 
that  the  subject  will  be  fully  elucidated  by  chemical 
enquiry.  Those  plants  which  seem  most  benefited  by 
its  application,  are  plants  which  always  afford  it  on 
analysis.  Clover,  and  most  of  the  artificial  grasses,  con- 
tain it,  but  it  exists  in  very  minute  quantity  only  in 
barley,  wheat  and  turnips.  Many  peat  ashes  which 
are  sold  at  a  considerable  price,  consist  in  great  part 
of  gypsum,  with  a  little  iron,  and  the  first  seems  to 
be  their  most  active  ingredient.  I  have  examined 
several  of  the  soils  to  which  these  ashes  are  success- 

D 


fully  applied,  and  I  have  found  in  them  no  sensible 
quantity  of  gypsum.  In  general,  cultivated  soils  contain 
sufficient  of  this  substance  for  the  use  of  the  grasses  ; 
in  such  cases,  its  application  cannot  be  advantageous. 
For  plants  require  only  a  certain  quantity  of  manure  ; 
an  excess  may  be  detrimental,  and  cannot  be  useful. 

The  theory  of  the  operation  of  alkaline  substan- 
ces, is  one  of  the  parts  of  the  chemistry  of  agriculture, 
most  simple  and  distinct.  They  are  found  in  all  plants 
and  therefore  may  be  regarded  as  amongst  their  es- 
sential ingredients.  From  their  powers  of  combina- 
tion likewise,  they  may  be  useful  in  introducing  vari- 
ous principles  into  the  sap  of  vegetables,  which  may 
be  subservient  to  their  nourishment. 

The  fixed  alkalies  which  were  formerly  regarded 
as  elementary  bodies,  it  has  been  my  good  fortune  to 
decompose.  They  consist  of  pure  air,  united  to  high- 
ly inflammable  metallic  substances  ;  but  there  is  no 
reason  to  suppose  that  they  are  reduced  into  their 
elements  in  any  of  the  processes  of  vegetation. 

In  this  part  of  the  course  I  shall  dwell  at  consi- 
derable length  on  the  important  subject  of  Lime,  and 
I  shall  be  able  to  oiFer  some  novel  views. 

Slacked  lime  was  used  by  the  Romans  for  man- 
uring the  soil  in  which  fruit  trees  grew.  This  we  are 
informed  by  Pliny.  Marie  had  been  employed  by  the 
Britons  and  the  Gauls  from  the  earliest  times,  as  a 
top  dressing  for  land.  But  the  precise  period  in 
which  burnt  lime  first  came  into  general  use  in  the  cul- 
tivation of  land,  is,  I  believe,  unknown.  The  origin 
of  the  application  from  the  early  practices  is  sufficient- 


C      19      3 

ly  obvious ;  a  substance  which  had  been  used  with 
success  in  gardening,  must  have  been  soon  tried  in 
in  farming ;  and  in  countries  where  marie  was  not  to 
be  found,  calcined  limestone  would  be  naturally  em- 
ployed as  a  substitute. 

The  elder  writers  on  agriculture  had  no  correct 
notions  of  the  nature  of  lime,  limestone  and  marie,  or 
of  their  effects  ;  and  this  was  the  necessary  conse* 
quence  of  the  imperfection  of  the  chemistry  of  the 
age.  Calcareous  matter  was  considered  by  the  alche- 
mists as  a  peculiar  earth,  which  in  the  fire  became 
combined  with  inflammable  acid ;  and  Evelyn  and 
Hartlib,  and  still  later.  Lisle,  in  their  works  on  hus- 
bandry, have  characterized  it  merely  as  a  hot  manure 
of  use  in  cold  lands.  It  is  to  Dr.  Black  of  Edinburgh 
that  our  first  distinct  rudiments  of  knowledge  on  the 
subject  are  owing.  About  the  year  1 755,  this  cele- 
brated professor  proved,  by  the  most  decisive  experi- 
ments, that  hmestone  and  all  its  modifications,  mar- 
bles, chalks,  and  marles,  consist  principally  of  a  pecu- 
liar earth  united  to  an  aerial  acid  :  that  the  acid  is 
given  out  in  burning,  occasioning  a  loss  of  more  than 
40  per  cent,,  and  that  the  lime  in  consequence  becomes 
caustic. 

These  important  facts  immediately  applied  with 
equal  certainty  to  the  explanation  of  the  uses  of  lime, 
both  as  a  cement  and  as  a  manure.  As  a  cement, 
lime  applied  in  its  caustic  state  acquires  its  hardness 
and  durability,  by  absorbing  the  aerial  (or  as  it  has 
been  since  called  carbonic)  acid,  which  always  exists 
in  small  quantities  in  the  atmosphere,  it  becomes  af^ 
it  were  again  limestone. 


C      20      3 

Chalks,  calcareous  marles,  or  powdered  lime- 
stones, act  merely  by  forming  an  useful  earthy  ingre- 
dient of  the  soil,  and  their  efficacy  is  proportioned  to 
the  deficiency  of  calcareous  matter,  which  in  larger 
or  smaller  quantities  seems  to  be  an  essential  ingre- 
dient of  all  fertile  soils  ;  necessary  perhaps  to  their 
proper  texture,  and  as  an  ingredient  in  the  organs  of 
plants. 

Burnt  lime,  in  its  first  effect,  acts  as  a  decompo- 
sing agent  upon  animal  or  vegetable  matter,  and  seems 
to  bring  it  into  a  state  on  which  it  becomes  more 
rapidly  a  vegetable  nourishment ;  gradually,  however, 
the  lime  is  neutralized  by  carbonic  acid,  and  conver- 
ted into  a  substance  analogous  to  chalk ;  but  in  this 
case  it  more  perfectly  mixes  with  the  other  ingredients 
of  the  soil,  is  more  generally  diffused  and  finely  di- 
vided ;  and  it  is  probably  more  useful  to  land  than 
any  calcareous  substance  in  its  natural  state. 

The  most  considerable  fact  made  known  with 
regard  to  limestone  within  the  last  few  years,  is  owing 
to  Mr.  Tennant.  It  had  been  long  known  that  a  par- 
ticular species  of  limestone  found  in  different  parts  of 
the  North  of  England,  when  applied  in  its  burnt  and 
slacked  state  to  land  in  considerable  quantities,  occa- 
sioned sterility,  or  considerably  injured  the  crops  for 
many  years.  Mr.  Tennant  in  1800,  by  a  chemical 
examination  of  this  species  of  limestone,  ascertained, 
that  it  differed  from  common  limestones  by  containing 
magnesian  earth ;  and  by  several  experiments  he 
proved  that  this  earth  was  prejudicial  to  vegetation, 
when  applied  in  large  quantities  in  its  caustic  state. 


r    21     ] 

Under  common  circumstances  the  lime  from  the  mag- 
nesian  limestone  is,  however,  used  in  moderate  quan- 
tities upon  fertile  soils  in  Leicestershire,  Derbyshire, 
and  Yorkshire,  with  good  effect ;  and  it  may  be  ap- 
plied in  greater  quantities  to  soils  containing  very  large 
proportions  of  vegetable  matter.  Magnesia  when 
combined  with  carbonic  acid  gas,  seems  not  to  be  pre- 
judicial to  vegetation,  and  in  soils  rich  in  manure,  it 
is  speedily  supplied  with  this  principle  from  the  de- 
composition of  the  manure. 

After  the  nature  and  operation  of  manures  have 
been  discussed,  the  next,  and  the  last  subject  for  our 
consideration,  will  be  some  of  the  operations  of  hus- 
bandry capable  of  elucidation  by  chemical  principles. 

The  chemical  theory  of  fallowing  is  very  simple. 
Fallowing  affords  no  new  source  of  riches  to  the  soil. 
It  merely  tends  to  produce  an  accumulation  of  decom 
posing  matter,  which  in  the  common  course  of  crops 
would  be  employed  as  it  is  formed,  and  it  is  scarcely 
possible  to  imagine  a  single  instance  of  a  cultivated 
soil,  which  can  be  supposed  to  remain  fallow  for  a 
year  with  advantage  to  the  farmer.  The  only  cases 
where  this  practice  is  beneficial  seems  to  be  in  the  des- 
truction of  weeds,  and  for  cleansing  foul  soils. 

The  chemical  theory  of  paring  and  burning,  I 
shall  discuss  fully  in  this  part  of  the  Course. 

It  is  obvious  that  in  all  cases  it  must  destroy  a 
certain  quantity  of  vegetable  matter,  and  must  be 
principally  useful  in  cases  in  which  there  is  an  excess 
of  this  matter  in  soils.  Burning,  likewise  renders 
clays  less  coherent,  and  in  this  way  greatly  improves 


C         22         3 

their  texture,  and  causes  them  to  be  less  permeable 
to  water. 

The  instances  in  which  it  must  be  obviously  pre- 
judicial, are  those  of  sandy  dry  siliceous  soils,  contain- 
ing little  animal  or  vegetable  matter,  fiere  it  can 
only  be  destructive,  for  it  decomposes  that  on  which 
the  soil  depends  for  its  productiveness. 

The  advantages  of  irrigation,  though  so  lately  a 
subject  of  much  attention,  were  well  known  to  the 
ancients  ;  and  more  than  two  centuries  ago  the  prac- 
tice was  recommended  to  the  farmers  of  our  country 
by  Lord  Bacon  ;  *'  meadow-watering,*'  according  to 
the  statements  of  this  illustrious  personage,  (given  in 
his  Natural  History,  in  the  article  Vegetation,)  acts 
not  only  by  supplying  useful  moisture  to  the  grass  ; 
but  likewise  the  water  carries  nourishment  dissolved 
in  it,  and  defends  the  roots  from  the  effects  of  cold. 

No  general  principles  can  be  laid  down  respecting 
the  comparative  merit  of  the  different  systems  of  culti- 
vation,  and  the  different  systems  of  crops  adopted  in 
different  districts,  unless  the  chemical  nature  of  the 
soil,  and  the  physical  circumstances  to  which  it  is  ex- 
posed are  fully  known.  Stiff  coherent  soils  are  those 
most  benefited  by  minute  division  and  aeration,  and  in 
the  drill  system  of  husbandry,  these  effects  are  pro- 
duced to  the  greatest  extent ;  but  still  the  labour  and 
expense  connected  with  its  application  in  certain  dis- 
tricts, may  not  be  compensated  for  by  the  advantages 
produced.  Moist  climates  are  best  fitted  for  raising 
the  artificial  grasses,  oats,  and  broad  leaved  crops  ; 
stiff  aluminous  soils,  in  general,  are  most  adapted  for 


C         23  ] 

wheat  crops,  and  calcareous  soils  produce  excellent 
sain-foin  and  cjover. 

Nothing  is  more  wanting  in  agriculture,  than  ex- 
periments in  which  all  the  circumstances  are  minutely 
and  scientifically  detailed.  This  art  will  advance  with 
rapidity  in  proportion  as  it  becomes  exact  in  its 
methods.  As  in  physical  researches  all  the  causes 
should  be  considered  ;  a  difference  in  the  results  may 
be  produced,  even  by  the  fall  of  a  half  an  inch  of  rain 
more  or  less  in  the  course  of  a  season,  or  a  few  de- 
grees of  temperature,  or  even  by  a  slight  difference  in 
the  sub-soil,  or  in  the  inclination  of  the  land. 

Information  collected  after  views  of  distinct  en- 
quiry, would  necessarily  be  more  accurate,  and  more 
capable  of  being  connected  with  the  general  principles 
of  science  ;  and  a  few  histories  of  the  results  of  truly 
philosophical  experiments  in  agricultural  chemistry, 
would  be  of  more  value  in  enlightening  and  benefitting 
the  farmer,  than  the  greatest  possible  accumulation  of 
imperfect  trials,  conducted  merely  in  the  empirical 
spirit.  It  is  no  unusual  occurence  for  persons  who 
argue  in  favour  of  practice  and  experience,  to  con- 
demn generally  all  attempts  to  improve  agriculture  by 
philosophical  enquiries  and  chemical  methods.  That 
much  vague  speculation  may  be  found  in  the  works  of 
those  who  have  lightly  taken  up  agricultural  chemis- 
try, it  is  impossible  to  deny.  It  is  not  uncommon  to 
find  a  number  of  changes  rung  upon  a  string  of  tech- 
nical terms,  such  as  oxygene,  hydrogene,  carbon,  and 
azote,  as  if  the  science  depended  upon  words,  rather 
than  upon  things.    But  this  is  in  fact  an  argument  for 


[  24  3 

the  necessity  of  the  establishment  of  just  principles  of 
chemistry  on  the  subject.  Whoever  reasons  upon 
agriculture,  is  obliged  to  recur  to  this  science.  He 
feels  that  it  is  scarcely  possible  to  advance  a  step  with- 
out it ;  and  if  he  is  satisfied  with  insufficient  views,  it 
is  not  because  he  prefers  them  to  accurate  knowledge, 
but  generally  because  they  are  more  current.  If  a 
person  journeying  in  the  night  wishes  to  avoid  being 
led  astray  by  the  ignis  fatuus,  the  most  secure  method 
is  to  carry  a  lamp  in  his  own  hand. 

It  has  been  said,  and  undoubtedly  with  great 
truth,  that  a  philosophical  chemist  would  most  proba- 
bly make  a  very  unprofitable  business  of  farming ;  and 
this  certainly  would  be  the  case,  if  he  were  a  mere 
philosophical  chemist ;  and  unless  he  had  served  his 
apprenticeship  to  the  practice  of  the  art,  as  well  as  to 
the  theory.  But  there  is  reason  to  believe,  that  he 
would  be  a  more  successful  agriculturist  than  a  per- 
son equally  uninitiated  in  farming,  but  ignorant  of 
chemistry  altogether ;  his  science,  as  far  as  it  went, 
would  be  useful  to  him.  But  chemistry  is  not  the 
only  kind  of  knowledge  required,  it  forms  a  small  part 
of  the  philosophical  basis  of  agriculture  ;  but  it  is  an 
important  part,  and  whenever  applied  in  a  proper 
manner  must  produce  advantages. 

In  proportion  as  science  advances  all  the  princi- 
ples become  less  complicated,  and  consequently  more 
useful.  And  it  is  then  that  their  application  is  most 
advantageously  made  to  the  arts.  The  common  la- 
bourer can  never  be  enlightened  by  the  general  doc- 
trines of  philosophy,  but  he  will  not  refuse  to  adopt 


C  25  2 

any  practice,  of  the  utility  of  which  he  is  fully  con- 
vinced, because  it  has  been  founded  upon  these  prin- 
ciples. The  mariner  can  trust  to  the  compass, 
though  he  may  be  wholly  unacquainted  with  the  dis- 
coveries of  Gilbert  on  magnetism,  or  the  refined  prin- 
ciples of  that  science  developed  by  the  genius  of 
^pinus.  The  dyer  will  use  his  bleaching  liquor, 
even  though  he  is  perhaps  ignorant  not  only  of  the 
constitution,  but  even  of  the  name  of  the  substance 
on  which  its  powers  depend.  The  great  purpose  of 
chemical  investigation  in  Agriculture,  ought  undoubt-  * 
edly  to  be  the  discovery  of  improved  methods  of  cul- 
tivation. But  to  this  end,  general  scientific  principles 
and  practical  knowledge,  are  alike  necessary.  The 
germs  of  discovery  are  often  found  in  rational  specu- 
lations ;  and  industry  is  never  so  efficacious  as  when 
assisted  by  science* 

•  It  is  from  the  higher  classes  of  the  community, 
from  the  proprietors  of  land  ;  those  who  are  fitted  by 
their  education  to  form  enlightened  plans,  and  by  their 
fortunes  to  carry  such  plans  into  execution  ;  it  is  from 
these  that  the  principles  of  improvement  must  flow  to 
the  labouring  classes  of  the  community ;  and  in  all 
cases  the  benefit  is  mutual ;  for  the  interest  of  the 
tenantry  must  be  always  likewise  the  interest  of  the 
proprietors  of  the  soil.  The  attention  of  the  labourer 
will  be  more  minute,  and  he  will  exert  himself  more 
for  improvement  when  he  is  certain  he  cannot  deceive 
his  employer,  and  has  a  conviction  of  the  extent  of 
his  knowledge.  Ignorance  in  the  possessor  of  an 
estate  of  the  manner  in  which  it  ought  to  be  treated. 


[         26         ] 

often  leads  either  to  inattention  or  injudicious  prac- 
tices in  the  tenant  or  the  bailiff.  ''  Agrum  pes- 
simiwi  mulctari  cujiis  Dominus  non  docet  sed  audit  vil- 

I'lcum,^* 

There  is  no  idea  more  unfonnded  than  that  a 
great  devotion  of  time,  and  minute  knowledge  of  gen- 
eral chemistry  is  necessary  for  pursuing  experiments 
on  the  nature  of  soils  or  the  properties  of  manures. 
Nothing  can  be  more  easy  than  to  discover  vi^hether  a 
soil  effervesces,  or  changes  colour  by  the  action  of  an 
acid,  or  whether  it  burns  when  heated  \  or  what 
weight  it  loses  by  heat :  and  yet  these  simple  indic;|L- 
tions  may  be  of  great  importance  in  a  system  of  culti- 
vation. The  expence  connected  with  chemical  enqui- 
ries is  extremely  trifling ;  a  small  closet  is  sufficient 
for  containing  all  the  materials  required.  The  most 
important  experiments  may  be  made  by  means  of  a 
small  portable  apparatus  ;  a  few  phials,  a  few  acids,  a 
lamp  and  a  crucible  are  all  that  are  necessary,  as  I  shall 
endeavour  to  prove  to  you,  in  the  course  of  these 
lectures. 

It  undoubtedly  happens  in  agricultural  chemical 
experiments  conducted  after  the  most  refined  theo- 
rectical  views,  that  there  are  many  instances  of  failure, 
for  one  of  success  ;  and  this  is  inevitable  from  the 
capricious  and  uncertain  nature  of  the  causes  that 
operate,  and  from  the  impossibility  of  calculating  on 
all  the  circumstances  that  may  interfere  ;  but  this  is 
far  from  proving  the  inutility  of  such  trials  \  one  hap- 
py result  which  can  generally  improve  the  methods 
of  cultivation  is  worth  the  labour  of  a  whole  life  ;  and 


C         27  3 

an  unsuccessful  experiment  well  observed,  must  esta- 
blish some  truth,  or  tend  to  remove  some  prejudice. 

Even  considered  merely  as  a  philosophical 
science,  this  department  of  knowledge  is  highly  worthy 
of  cultivation.  For  what  can  be  more  delightful  than 
to  trace  the  forms  of  living  beings  and  their  adapta- 
tions and  peculiar  purposes  j  to  examine  the  progress 
of  inorganic  matter  in  its  different  processes  of 
change,  till  it  attain  its  ultimate  and  highest  destina- 
tion ;  its  subserviency  to  the  purposes  of  man. 

Many  of  the  sciences  are  ardently  pursued,  and 
tonsidered  as  proper  objects  of  study  for  all  refined 
minds,  merely  on  account  of  the  intellectual  pleasure 
they  afford  ;  merely  because  they  enlarge  our  views 
of  nature,  and  enable  us  to  think  more  correctly  with 
respect  to  the  beings  and  objects  surrounding  us.  How 
much  more  then  is  this  department  of  enquiry  worthy 
of  attention,  in  which  the  pleasure  resulting  from  the 
love  of  truth  and  of  knowledge  is  as  great  as  in  any 
other  branch  of  philosophy,  and  in  which  it  is  likewise 
connected  with  much  greater  practical  benefits  and 
advantages.  "  Nihil  est  melius^  nihil  uberius^  nihil  ho- 
mine  liber o  digniusJ' 

Discoveries  made  in  the  cultivation  of  the  earth, 
are  not  merely  for  the  time  and  country  in  which  they 
are  developed,  but  they  may  be  considered  as  extend- 
ing to  future  ages,  and  as  ultimately  tending  to  bene- 
fit the  whole  human  race ;  as  affording  subsistence 
for  generations  yet  to  come  ;  as  multiplying  life,  and 
not  only  multiplying  life,  but  likewise  providing  for 
its  enjoyment. 


28 


LECTURE  IL 

Of  the  general  Powers  of  Matter  which  influence  Vegeta- 
tion, Of  Gravitationy  of  Cohesion ^  of  chemical  Attrac- 
iion^  of  Heat^  of  Lights  of  Electricity ^  ponderable 
Substances^  Elements  of  Matter^  particularly  those 
found  in  Vegetables^  Laws  of  their  Combinations  and 
Arrangements. 

THE  great  operations  of  the  farmer  are  directed 
towards  the  production  or  improvement  of  certain 
classes  of  vegetables  j  they  are  either  mechanical  or 
chemical,  and  are,  consequently,  dependant  upon  the 
laws  which  govern  common  matter.  Plants  themselves 
are,  to  a  certain  extent,  submitted  to  these  hws ;  and 
it  is  necessary  to  study  their  effects  both  in  consider- 
ing the  phasnomena  of  vegetation,  and  the  cultivation 
of  the  vegetable  kingdom. 

One  of  the  most  important  properties  belonging 
to  matter  is  gravitation^  or  the  power  by  which  mas- 
ses of  matter  are  attracted  towards  each  other.  It  is 
in  consequence  of  gravitation  that  bodies  thrown  into 
the  atmosphere  fall  to  the  surface  of  the  earth,  and  that 
the  different  parts  of  the  globe  are  preserved  in  their 
proper  positions.  Gravity  is  exerted  in  proportion  to 
the  quantity  of  matter.  Hence  all  bodies  placed  above 
the  surface  of  the  earth  fall  to  it  in  right  lines,  which 
if  produced  would  pass  through  its  centre  j   and  a 


[         29         3 

body  falling  near  a  high  mountain,  is  a  little  bent 
out  of  the  perpendicular  direction  by  the  attraction 
of  the  mountain,  as  has  been  shewn  by  tbe  experi- 
ments of  Dr.  Maskelyne  on  Schehallien. 

Gravitation  has  a  very  important  influence  on 
the  growth  of  plants  ;  and  it  is  rendered  probable,  by 
the  experiments  of  Mr.  Knight,  that  they  owe  the  pe- 
culiar direction  of  their  roots  and  branches  almost  en- 
tirely to  this  force. 

That  gentleman  fixed  some  seeds  of  the  garden 
bean  on  the  circumference  of  a  wheel,  which  in  one 
instance  was  placed  vertically,  and  in  the  other  hori- 
zontally, and  made  to  revolve,  by  means  of  another 
wheel  worked  by  water,  in  such  a  manner,  that  the 
number  of  the  revolutions  could  be  regulated ;  the 
beans  were  supplied  with  moisture,  and  were  placed 
under  circumstances  favourable  to  germination.  The 
greatest  velocity  of  motion  given  to  the  wheel  was 
such,  that  it  performed  250  revolutions  in  a  minute. 
It  was  found  that  in  all  cases  the  beans  grew,  and  that 
the  direction  of  the  roots  and  stems  was  influenced  by 
the  motion  of  the  wheel.  When  the  centrifugal  force 
was  made  superior  to  the  force  of  gravitation,  which 
was  supposed  to  be  done  when  the  vertical  wheel  per- 
formed 1 50  revolutions  in  a  minute,  all  the  radicles, 
in  whatever  way  they  were  protruded  from  the  po- 
siticn  of  the  seeds,  turned  their  points  outwards  from 
the  circumference  of  the  wheel,  and  in  their  subse- 
quent growth  receded  nearly  at  right  angles  from  its 
axis ;  the  germens,  on  the  contrary,  took  the  opposite 
direction,  and  in  a  few  days  their  points  all  met  in 
the  centre  of  the  wheel. 


C       so       3 

When  the  centrifugal  force  was  made  merely  •  to 
modify  the  force  of  gravitation  in  the  horizontal  wheel 
when  the,greatest  volocity  of  revolution  was  given, 
the  radicles  pointed  downwards  about  ten  degrees  be- 
low, and  the  germens  as  many  degrees  above  the 
horizontal  line  of  the  wheel's  motion ;  and  the  devia- 
tion from  the  perpendicular  was  less  in  proportion, 
as  the  motion  was  less  rapid.* 

These  facts  afford  a  rational  solution  of  this  cu- 
rious problem,  respecting  which  different  philosophers 
have  given  such  different  opinions ;  some  referring  it 
to  the  nature  of  the  sap,  as  De  la  Hire,  others,  as 
Darwin,  to  the  living  powers  of  the  plant,  and  the 
stimulus  of  air  upon  the  leaves,  and  of  moisture  upon 
the  roots.  The  effect  is  now  shewn  to  be  connected 
with  mechanical  causes ;  and  there  seems  no  other 
power  in  nature  to  which  it  can  with  propriety  be 
referred  but  gravity,  which  acts  universally,  and 
which  must  tend  to  dispose  the  parts  to  take  a  uni- 
form direction. 

If  plants  in  general  owe  their  perpendicular  di- 
rection to  gravity,  it  is  evident  that  the  number  of 
plants  upon  a  given  part  of  the  earth's  circumference, 
cannot  be  increased  by  making  the  surface  irregular, 
as  some  persons  have  supposed.  Nor  can  more  stalks 
rise  on  a  hill  than  on  a  spot  equal  to  its  base  ;  for  the 
slight  effect  of  the  attraction  of  the  hill,  would  be  only 


•  Fig.  1  represents  the  form  of  the  experiment  v/hen  the  vertical  wheel  was 
made  to  perform  ISO  revolutions  in  a  minute. 

Fig.  2  represents  the  case  in  which  the  horizental  wheel  perfornied  250  vevo- 
latlons. 


p.  50 


[  31  ] 

to  make  the  plats  deviate  a  very  little  from  the  per- 
pendicular. Where  horizontal  layers  are  pushed 
forth,  as  in  certain  grasses,  particularly  such  as  the 
fiorin,  lately  brought  into  notice  by  Dr.  Richardson, 
more  food  may,  however,  be  produced  upon  an  irre- 
gular surface  ;  but  the  principle  seems  to  apply  strict- 
ly to  corn  crops.  * 

The  direction  of  the  radicles  and  germens  is  such 
that  both  are  suppHed  with  food,  and  acted  upon  by 
those  external  agents  which  are  necessary  for  their 
developement  and  growth.  The  roots  come  in  con- 
tact with  the  fluids  in  the  ground  ;  the  leaves  are  ex- 
posed to  light  and  air ;  and  the  same  grand  law  which 
preserves  the  planets  in  their  orbits,  is  thus  essential 
to  the  functions  of  vegetable  life. 

When  two  pieces  of  polished  glass  are  pressed 
together  they  adhere  to  each  other,  and  it  requires 
some  force  to  separate  them.  This  is  said  to  depend 
upon  the  attraction  of  cohesion.  The  same  attraction 
gives  the  globular  form  to  drops  of  water,  and  enables 
fluids  to  rise  in  capillary  tubes  ;  and  hence  it  is  some- 
times called  capillary  attraction.  This  attraction,  like 
gravitation,  seems  common  to  all  matter,  and  may  be 
a  modification  of  the  same  general  force  ;  like  gravi- 
tation, it  is  of  great  importance  in  vegetation.  It  pre- 
serves the  forms  of  aggregation  of  the  parts  of  plants^ 
and  it  seems  to  be  a  principal  cause  of  the  absorption 
of  fluids  by  their  roots. 

If  some  pure  magnesia,  the  calcined  magnesia  of 
druggists,  be  thrown  into  distilled  vinegar,  it  gradu- 
ally disolves.     This  is  said  to  be  owing  to  che?nical 


C         32         ] 

attraction^  the  power  by  which  difFerent  species  of 
matter  tend  to  unite  into  one  compound.  Various 
kinds  of  matter  unite  with  different  degrees  of  force : 
thus  sulphuric  acid  and  magnesia  unite  with  more 
readiness  than  distilled  vinegar  and  magnesia  ;  and  if 
sulphuric  acid  be  poured  into  a  mixture  of  vinegar 
and  magnesia,  in  which  the  acid  properties  of  the 
vinegar  have  been  destroyed  by  the  magnesia,  the  vine- 
gar  will  be  set  free,  and  the  sulphuric  acid  will  take 
its  place.  This  chemical  attraction  is  Hkewise  called 
chemical  affinity.  It  is  active  in  most  of  the  phseno- 
mena  of  vegetation.  The  sap  consists  of  a  number  of 
ingredients,  dissolved  in  water  by  chemical  attraction  ; 
and  it  appears  to  be  in  consequence  of  the  operation 
of  this  power,  that  certain  principles  derived  from  the 
sap  are  united  to  the  vegetable  organs.  By  the  laws 
of  chemical  attraction,  different  products  of  vegetation 
are  changed,  and  assume  new  forms:  the  food  of 
plants  is  prepared  in  the  soil  5  vegetable  and  animal 
remains  are  changed  by  the  action  of  air  and  water, 
and  made  fluid  or  aeriform  ;  rocks  are  broken  down 
and  converted  into  soils  ;  and  soils  are  more  finely 
divided  and  fitted  as  receptacles  for  the  roots  of 
plants. 

The  different  powers  of  attraction  tend  to  pre- 
serve the  arrangements  of  matter,  or  to  unite  them  in 
new  forms.  If  there  were  no  opposing  powers,  there 
would  soon  be  a  state  of  perfect  quiescence  in  nature, 
a  kind  of  eternal  sleep  in  the  physical  world.  Gravi- 
tation is  continually  counteracted  by  mechanical 
agencies,  by  projectile  motion,    or   the    centrifugal 


i  33  3 

Ibrce  ;  and  their  joint  agencies  occasion  the  motion  of 
the  heavenly  bodies.  Cohesion  and  chemical  attrac- 
tion are  opposed  by  the  repulsive  energy  of  heat^  and 
the  harmonious  cycle  of  terrestrial  changes  is  pro- 
duced by  their  mutual  opf  rations. 

Heat  is  capable  of  being  communicated  from  one 
body  to  other  bodies;  and  its  common  effect  is  to 
expand  them,  to  enlarge  them  in  all  their  dimensions. 
This  is  easily  exemplified.  A  solid  cylinder  of  metal 
after  being  heated  will  not  pass  through  a  ring  barely 
sufficient  to  receive  it  when  cold.  When  water  is 
heated  in  a  globe  of  glass  having  a  long  slender  neck, 
it  rises  in  the  neck  ;  and  if  heat  be  appUed  to  air  con- 
fined in  such  a  vessel  inverted  above  water,  it  makes 
its  escape  from  the  vessel  and  passes  through  the  wa- 
ter. Thermometers  are  instruments  for  measuring 
degrees  of  heat  by  the  expansion  of  fluids  in  narrow 
tubes.  Mercury  is  generally  used,  of  which  100,000 
parts  at  the  freezing  point  of  water  become  101,83.g; 
parts  at  the  boiling  point,  and  on  Fahrenheit's  scale 
these  parts  are  divided  into  180  degrees.  Solids,  by 
a  certain  increase  of  heat,  become  fluids,  and  fluids 
gasses,  or  elastic  fluids.  Thus  ice  is  converted  by  heat 
into  water,  and  by  still  more  heat  it  becomes  steam  : 
and  heat  disappears,  or,  as  it  is  called,  is  rendered! 
latent  during  the  conversion  of  solids  into  fluids,  or 
fluids  into  gasses,  and  reappears  or  becomes  sensible 
when  gasses  become  fluids,  or  fluids  solids :  hence 
cold  is  produced  during  evaporation,  and  heat  during 
the  condensation  of  steam. 

F 


C         34         3 

There  are  a  few  exceptions  to  the  law  of  expansion 
of  bodies  by  heat,  which  seem  to  depend  either  upon 
some  change  in  their  chemical  constitution,  or  on  their 
becoming  crystallized.  Clay  contracts  by  heat, 
which  seems  to  be  owing  to  its  giving  off  water.  Cast 
iron  and  antimony,  when  melted,  crystallize  in  cool- 
ing and  expand.  Ice  is  much  lighter  than  water. 
Water  expands  a  little  even  before  it  freezes,  and  it  is 
of  the  greatest  density  at  about  41°  or  42°,  the  freez- 
ing point  being  S2° ;  and  this  circumstance  is  of  con- 
siderable importance  in  the  general  oeconomy  of  na- 
ture. The  influence  of  the  changes  of  seasons  and 
of  the  position  of  the  sun  on  the  phaenomena  ©f  vege- 
tation, demonstrates  the  effects  of  heat  on  the  func- 
tions of  plants.  The  matter  absorbed  from  the  soil 
must  be  in  a  fluid  state  to  pass  into  their  roots,  and 
•when  the  surface  is  fwzen  they  can  derive  no  nour- 
ishment from  it.  The  activity  of  chemical  changes 
likewise  is  increased  by  a  certain  increase  of  tempera- 
ture, and  even  the  rapidity  of  the  ascent  of  fluids  by 
capillary  attraction. 

This  last  fact  is  easily  shewn  by  placing  in  each 
of  two  wine  glasses  a  similar  hollow  stalk  of  grass,  so 
bent  as  to  discharge  any  fluid  in  the  glasses  slowly  by 
capillary  attraction  ;  if  hot  water  be  in  one  glass,  and 
cold  water  in  the  other,  the  hot  water  will  be  dis- 
charged much  more  rapidly  than  the  cold  water.  The 
fermentation  and  decomposition  of  animal  and  vegeta* 
ble  substances  require  a  certain  degree  of  heat,  which 
is  consequently  necessary  for  the  preparation  of  the 
food  of  plants  ;  and  as  evaporation  is  more  rapid  in 


C  35  ] 

proportion  as  the  temperature  is  higher,  the  superflu- 
ous parts  of  the  sap  are  most  readily  carried  off  at  the 
time  its  ascent  is  quickest. 

Two  opinions  are  current  respecting  the  nature 
of  heat.  By  some  philosophers  it  is  conceived  to  be 
a  pecuHar  subtile  fluid,  of  which  the  particles  repel 
each  other,  but  have  a  strong  attraction  for  the  parti- 
cles of  other  matter.  By  others  it  is  considered  as 
a  motion  or  vibration  of  the  particles  of  matter, 
which  is  supposed  to  differ  in  velocity  in  different 
cases,  and  thus  to  produce  the  different  degrees  of 
temperature.  Whatever  decision  be  ultimately  made 
respecting  these  opinions,  it  is  certain  that  there  is 
matter  moving  in  the  space  betvi^een  us  and  the  hea- 
venly bodies  capable  of  communicating  heat  5  the  mo- 
tions of  which  are  rectilineal :  thus  the  solar  rays 
produce  heat  in  acting  on  the  surface  of  the  earth. 
The  beautiful  experiments  of  Dr.  Herschel  have 
shewn  that  there  are  rays  transmitted  from  the  sun 
which  do  not  illuminate  ;  and  which  yet  produce 
more  heat  than  the  visible  rays  ;  and  Mr.  Ritter  and 
Dr.  Wollaston  have  shewn  that  there  are  other  invisi* 
ble  rays  distinguished  by  their  chemical  effects. 

The  different  influence  of  the  different  solar  rays 
on  vegetation  have  not  yet  been  studied  \  but  it  is  cer- 
tain that  the  rays  exercise  an  influence  independent  of 
the  heat  they  produce.  Thus  plants  kept  in  the  dark 
in  a  hot-house  grow  luxuriantly,  but  they  never  gain 
their  natural  colours  ;  their  leaves  are  white  or  pale, 
and  their  juices  watery  and  peculiarly  saccharine. 


C         36         3 

When  a  piece  of  sealing-wax  is  rubbed  by  z 
^Toollen  cloth,  it  gains  the  power  of  attracting  light 
bodies,  such  as  feathers  or  ashes.  In  this  state  it  is 
said  to  be  electrical ;  and  if  a  metallic  cylinder,  placed 
upon  a  rod  of  glass,  is  brought  in  contact  with  the 
sealing-wax,  it  likewise  gains  the  momentary  power  of 
attracting  light  bodies,  so  that  electricity  like  heat  is 
communicable.  When  two  light  bodies  receive  the 
same  electrical  influence,  or  are  electrified  by  the 
same  body,  they  repel  each  other.  When  one  of  them 
is  acted  on  by  sealing-wax,  and  the  other  by  glass  that 
has  been  rubbed  by  woollen,  they  attract  each  other ; 
hence  it  is  said,  that  bodies  similarly  electrified  repel 
each  other,  and  bodies  dissimilarly  electrified  attract 
each  other  :  and  the  electricity  of  glass  is  called 
vitreous  or  positive  electricity,  and  that  of  sealing-wax 
resinous  or  negative  electricity. 

Vf  hen  of  two  bodies  made  to  rub  each  other  one 
is  found  positively  electrified,  the  other  is  always 
found  negatively  electrified,  and,  as  in  the  common 
electrical  machine,  these  states  are  capable  of  being 
communicated  to  metals  placed  upon  rods  or  pillars  of 
glass.  Electricity  is  produced  likewise  by  the  contact 
of  bodies  ;  thus  a  piece  of  zinc  and  of  silver  give  a 
slight  electrical  shock  when  they  are  made  to  touch 
each  other,  and  to  touch  the  tongue  :  and  when  a 
number  of  plates  of  copper  and  zinc,  1 00  for  instance, 
are  arranged  in  a  pile  with  cloths  moistened  in  salt  and 
water,  in  the  order  of  zinc,  copper,  moistened  cloth, 
zinc,  copper,  moistened  cloth,  and  so  on,  they  form 
an  electrical  battery  which  will  give  strong  shocka 


C         37         ] 

and  sparks,  and  which  is  possesed  of  remarkable 
chemical  powers.  The  luminous  phasnomena  pro- 
duced by  common  electricity  are  well  known.  It 
would  be  improper  to  dwell  upon  them  in  this 
place.  They  are  the  most  impressive  effects  occa- 
sioned  by  this  agent ;  and  they  offer  illustrations 
of  lightning  and  thunder. 

Electrical  changes  are  constantly  taking  place  in 
nature,  on  the  surface  of  the  earth  and  in  the  atmos- 
phere ;  but  as  yet  the  effects  of  this  power  in  vegeta- 
tion have  not  been  correctly  estimated.  It  has  been 
shewn  by  experiments  made  by  means  of  the  Voltaic 
battery  (the  instrument  composed  of  zinc,  copper,  and 
water),  that  compound  bodies  in  general  are  capable 
of  being  decomposed  by  electrical  powers,  and  it  is 
probable,  that  the  various  electrical  phasnomena  oc- 
curring in  our  system,  must  influence  both  the  ger- 
mination of  seeds  and  the  growth  of  plants.  I  found 
that  corn  sprouted  much  more  rapidly  in  water  posi- 
tively electrified  by  the  Voltaic  instrument  than  in 
water  negatively  electrified;  and  experiments  made 
upon  the  atmosphere  shew  that  clouds  are  usually  ne- 
gative ;  tand  as  when  a  cloud  is  in  one  state  of  elec- 
tricity the  surface  of  the  earth  beneath  is  brought  into 
the  opposite  state,  it  is  probable  that  in  common  cases 
the  surface  of  the  earth  is  positive. 

Different  opinions  are  entertained  amongst  scien-* 
tific  men  respecting  the  nature  of  electricity ;  by  some, 
the  phsenomena  are  conceived  to  depend  upon  a  single 
subtile  fluid  in  excess  in  the  bodies  said  to  be  posi- 
tively electrified,  in  deficiency  in  the  bodies  said  to  be 


t  88  3 

negatively  electrified.  A  second  class  suppose  the 
eftects  to  be  produced  by  two  different  fluids,  called 
by  them  the  vitreous  fluid  and  the  resinous  fluid  ;  and 
others  regard  them  as  affections  or  motions  of  matter, 
or  an  exhibition  of  attractive  povi^ers,  similar  to  those 
which  produce  chemical  combination  and  decomposi- 
tion ;  but  usually  exerting  their  action  on  masses. 

The  different  powers  that  have  been  thus  gener- 
ally described,  continually  act  upon  common  matter 
so  as  to  change  its  form  and  produce  arrangements 
fitted  for  the  purposes  of  life.  Bodies  are  either  sim- 
ple or  compound.  A  body  is  said  to  be  simple,  when 
it  is  incapable  of  being  resolved  into  any  other  fbrms 
of  matter.  Thus  gold,  or  silver,  though  they  may 
be  melted  by  heat  or  dissolved  in  corrosive  menstrua, 
yet  are  recovered  unchanged  in  their  properties,  and 
they  are  said  to  be  simple  bodies.  A  body  is  consi- 
dered as  compound,  when  two  or  more  distinct  sub- 
stances are  capable  of  being  produced  from  it ;  thus 
marble  is  a  compound  body,  for  by  a  strong  heat,  it  is 
converted  into  Hme,  and  an  elastic  fluid  is  disengaged 
in  the  process  :  and  the  proof  of  our  knowledge  of 
the  true  composition  of  a  body  is,  that  it  is  capable  of 
being  reproduced  by  the  same  substances  as  those  into 
which  it  had  been  decomposed  ;  thus  by  exposing 
lime  for  a  long  while  to  the  elastic  fluid,  disengaged 
during  its  calcination,  it  becomes  converted  into  a  sub- 
stance similar  to  powdered  marble.  The  term  element 
has  the  same  meaning  as  simple  or  undecompounded 
body  ;  but  it  is  applied  merely  with  reference  to  the 
present  state  of  chemical  knowledge.     It  is  probable. 


C      S9      3 

that  as  yet  we  are  not  acquainted  with  any  of  the  true 
elements  of  matter ;  many  substances,  formerly  sup- 
posed to  be  simple,  have  been  lately  decompounded, 
and  the  chemical  arrangement  of  bodies  must  be  con- 
sidered as  a  mere  expression  of  facts,  the  results  of 
accurate  statical  experiments. 

Vegetable  substances  in  general  are  of  a  very 
compound  nature,  and  consist  of  a  great  number  of 
elements,  most  of  which  belong  likewise  to  the  other 
kingdoms  of  nature,  and  are  found  in  various  forms. 
Their  more  complicated  arrangements  are  best  under- 
stood after  their  simpler  forms  of  combination  have 
been  examined. 

The  number  of  bodies  which  I  shall  consider  as 
at  present  undecomposed,  are,  as  was  stated  in  the 
introductory  lecture,  two  gasses  that  support  combus- 
bustion,  seven  inflammable  bodies,  and  thirty-eight 
metals. 

In  most  of  the  inorganic  compounds,  the  nature 
of  which  is  well  known,  into  which  these  elements 
enter,  they  are  combined  in  definite  proportions  ;  so 
that  if  the  elements  be  represented  by  numbers,  the 
proportions  in  which  they  combine  are  expressed 
either  by  those  numbers,  or  by  some  simple  multiples 
of  them. 

I  shall  mention,  in  few  words,  the  characteristic 
properties  of  the  most  important  simple,  substances, 
and  the  numbers  representing  the  proportions  in 
which  they  combine  in  those  cases,  wher^  they  have 
been  accurately  ascertained. 


C       40      3 

1.  Oxygene  forms  about  one-fifth  of  the  air  of  our 
atmosphere.  It  is  an  elastic  fluid,  at  all  known  tem- 
peratures. Its  specific  gravity  is  to  that  of  air  as  10967 
to  10000.  It  supports  combustion  with  much  more 
vividness  than  common  air;  so  that  if  a  small  steel 
wire,  or  a  watch  spring,  having  a  bit  of  inflamed  wood 
attached  to  it,  be  introduced  into  a  bottle  filled  with 
the  gas,  it  burns  with  great  splendour.  It  is  respirable. 
It  is  very  slightly  soluble  in  water.  The  number  re- 
presenting the  proportion  in  which  it  combines  is  1 5. 
It  may  be  made  by  heating  a  mixture  of  the  mineral 
called  manganese,  and  sulphuric  acid  together,  in  a 
proper  vessel,  or  by  heating  strongly  red  lead,  or  red 
precipitate  of  mercury. 

2.  Chlorine^  or  oxymuriatic  gas,  is  like  oxygene,  a 
permanent  elastic  fluid.  Its  colour  is  yellowish  green, 
its  smell  is  very  disagreeable  ;  it  is  not  respirable  ;  it 
supports  the  combustion  of  all  the  common  inflam- 
mable bodies  except  charcoal ;  its  specific  gravity 
is  to  that  of  air  as  24677  to  10000 ;  it  is  soluble 
in  about  half  its  volume  of  water,  atid  its  solution  in 
water  destroys  vegetable  colours.  Many  of  the 
metals  (such  as  arsenic  or  copper)  take  fire  spon- 
taneously when  introduced  into  a  jar  or  bottle  filled 
with  the  gas.  Chlorine  may  be  procured  by  heating 
together  a  mixture  of  spirits  of  salt  or  muriatic  acid, 
and  manganese.  The  number  representing  the  pro- 
portion in  which  this  gas  enters  into  combination 
is  67. 

3.  HydrogenSy  or  inflammable  air,  is  the  lightest 
known  substance  ;  its  specific  gravity  is  to  that  of  air 


C      41      3 

as  732  to  10000.  It  burns  by  the  action  of  an  in- 
flamed taper,  when  in  contact  with  the  atmosphere. 
The  proportion  in  which  it  combines  is  represented  by 
unity,  or  1.  It  is  procured  by  the  action  of  diluted  oil 
of  vitriol,  or  hydro  sulphuric  acid  on  filings  of  zinc  or 
iron.  It  is  the  substance  employed  for  filling  air  bal- 
loons. 

4.  Azote  is  a  gaseous  substance  not  capable  of 
being  condensed  by  any  known  degree  of  cold  :  its 
specific  gravity  is  to  that  of  common  air  as  95 1 6  to 
10000.  It  does  not  enter  into  combustion  under 
common  circumstances,  but  may  be  made  to  unite 
with  oxygene  by  the  agency  of  electrical  fire.  It  forms 
nearly  four  fifths  of  th,e  air  of  the  atmosphere  \  and 
may  be  procured  by  burning  phosphorus  in  a  confin- 
ed portion  of  air.  The  number  representing  the  pro- 
portion in  which  it  combines  is  26. 

5.  Carbon  is  considered  as  the  pure  matter  of 
charcoal,  and  it  may  be  produced  by  passing  spirits  of 
wine  through  a  tube  heated  red.  It  has  not  yet  been 
fused  ;  but  rises  in  vapour  at  an  intense  heat.  Its 
specific  gravity  cannot  be  easily  ascertained  ;  but  that 
of  the  diamond,  which  cannot  chemically  be  distin- 
guished from  pure  carbon,  is  to  that  of  water  as  3500 
to  1000.  Charcoal  has  the  remarkable  property  of 
absorbing  several  times  its  volume  of  different  elastic 
fluids  which  are  capable  of  being  expelled  from  it  by 
heat.     The  number  representing  it  is  11 .4. 

6.  Sulphur  is  the  pure  substance  so  well  known 
by  that  name  :  its  specific  gravity  is  to  that  of  water 
as  1990  to  1000.     It  fuses  at  about  220*^  Fahrenheit  5 

G 


C         42         3 

and  at  between  v500"  and  600°  takes  fire,  if  in  contact 
with  the  air,  and  burns  with  a  pale  blue  flame.  In  this 
process  it  dissolves  in  the  oxygene  of  the  air,  and  pro- 
duces a  peculiar  acid  elastic  fluid.  The  number  re- 
presenting it  is  30. 

7.  Pho&phorus  is  a  solid  of  a  pale  red  colour,  of 
specific  gravity  1770.  It  fuses  at  90",  and  boils  at 
550°.  It  is  luminous  in  the  air  at  common  tempera- 
tures, and  burns  with  great  violence  at  1 50°,  so  that 
it  must  be  handled  with  great  caution.  The  number 
representing  it  is  20.  It  is  procured  by  digesting 
together  bone  ashes  and'  oil  of  vitriol,  and  strongly 
heating  the  fluid  substance  so  produced  with  powdered 
charcoal. 

8.  Boron  is  a  solid  of  a  dark  olive  colour,  infu- 
sible  at  any  known  temperature.  It  is  a  substance 
very  lately  discovered,  and  procured  from  boracic 
acid.  It  burns  with  brilliant  sparks,  when  heated  in 
oxygene,  but  not  in  chlorine.  Its  specific  gravity, 
and  the  number  representing  it,  are  not  yet  accurately 
known. 

9.  Platinum  is  one  of  the  noble  metals,  of  rather 
a  duller  white  than  silver,  and  the  heaviest  body  in 
nature  ;  its  specific  gravity  being  2 1 500.  It  is  not 
acted  upon  by  any  acid  menstrua  except  such  as  con- 
tain chlorine  :  It  requires  an  intense  degree  gf  heat 
for  its  fusion. 

10.  The  properties  o^  gold  are  well  known.  Its 
specific  gravity  is  19277.  It  bears  the  same  relation 
to  acid  menstrua  as  platinum  :  it  is  one  of  the  char- 
acteristics of  both  these  bodies,  that  they  are  very  dif- 
cultly  acted  upon  by  sulphur. 


C      ^3       ] 

1 1 .  Silver  Is  of  specific  gravity  1 0400,  it  burns 
more  readily  than  plantinum  or  gold,  which  require 
the  intense  heat  of  electricity.  It  readily  unites  to 
sulphur..    The  number  representing  it  is  205. 

12.  Mercury  is  the  only  known  metal  fluid  at 
the  common  temperature  of  the  atmosphere  ;  it  boils 
at  66  ""j  and  freezes  at  39'^  below  0.  Its  specific  gra- 
vity is  1356  .     The  number  representing  it  is  380. 

13.  Copper  is  of  specific  gravity  8890.  It  burns 
when  strongly  heated  with  red  flame  tinged  with 
green.     The  number  representing  it  is  1  i^O. 

14.  Cobalt  is  of  specific  gravity  7700.  Irs  point 
of  fusion  is  very  high,  nearly  equal  to  that  of  iron. 
In  its  calcined  or  oxidated  state,  it  is  employed  for 
giving  a  blue  colour  to  glass. 

15.  Nickel  is  of  a  white  colour  :  its  specific  gra- 
vity is  8820.  This  metal  and  cobalt  agree  with  iron,  in 
feeing  attractible  by  the  magnet.  The  number  repre- 
senting nickel  is  111. 

16.  Iron  is  of  specific  gravity  7700.  Its  other 
properties  are  well  known.  The  number  represent- 
ing it  is  103. 

17.  Tin  is  of  specific  gravity  7291  ;  it  is  a  very 
fusible  metal,  and  burns  when  ignited  in  the  air  :  the 
number  representing  the  proportion  in  which  it  com- 
bines is  11 0. 

1 8.  Zinc  is  one  of  the  most  combustible  of  the 
common  metals.  Its  specific  gravity  is  about  7210. 
It  is  brittle  metal  under  common  circumstances  ;  but 
when  heated  inay  be  hammered  or  rolled  into  thin 
leaves,  and  after  this  operation  is  malleable.  The  num- 
ber representing  it  is  66. 


C  44  ] 

1 9.  Lead  is  of  specific  gravity  1 1 352  ;  it  fuses 
at  a  temperature  rather  higher  than  tin.  The  num- 
ber representing  it  is  398. 

20.  Bisjnuth  is  a  brittle  metal  of  specific  gravity 
9822.  It  is  nearly  as  fusible  as  tin  ;  when  cooled 
slowly  it  crystallizes  in  cubes.  The  number  repre- 
senting it  is  I S5. 

21.  Antimony  is  a  metal  capable  of  being  volat- 
ilized by  a  strong  red  heat.     Its  specific  gravity  is 

6800.     It  burns  when  ignited  with  a  faint  white  light. 
The  number  representing  it  is  170. 

22.  Arse?iic  is  of  a  blueish  white  colour,  of 
specific  gravity  8310.  It  may  be  procured  by  heating 
the  powder  of  common  white  arsenic  of  the  shops 
strongly  in  a  Florence  flask  with  oil.  The  metal  rises 
in  vapour,  and  condenses  in  the  neck  of  the  flask. 
The  number  representing  it  is  90. 

23.  Manganesiim  may  be  procured  from  the 
mineral  called  manganese,  by  intensely  igniting  it  in 
a  forge  mixed  with  charcoal  powder.  It  is  a  metal 
very  difhcult  of  fusion,  and  very  combustible  ;  its 
specific  gravity  is  6850.  The  number  representing  it 
is  177. 

24.  Potassium  is  the  lightest  known  metal,  being 
only  of  specific  gravity  850.  It  fuses  at  about  150% 
and  rises  in  vapour  at  a  heat  a  little  below  redness, 
It  is  a  highly  combustible  substance,  takes  fire  when 
thrown  Tipon  water,  burns  with  great  brilliancy,  and 
the  product  of  its  combustion  dissolves  in  the  water. 
The  number  representing  it  is  75.  It  may  be  made 
by  passing  fused  caustic  vegetable  alkali,  (the  pure  kali 


C         4f        ] 

qf  druggists)  through  iron  turnings  strongly  ignited 
in  a  gun  barrel,  or  by  the  electrization  of  potash  by  a 
strong  Voltaic  battery. 

25.  Sodium  may  be  made  in  a  similar  manner  to 
potassium.  Soda  or  the  mineral  alkali  being  substituted 
for  the  vegetable  alkali.  It  is  of  specific  gravity  940. 
It  is  very  combustible.  When  thrown  upon  water, 
it  swims  on  its  surface,  hisses  violently,  and  dissolves, 
but  does  not  inflame.  The  number  representing  it 
is  88. 

26.  Barium  has  as  yet  been  procured  only  by 
electrical  powers  and  in  very  minute  quantities,  so  that 
its  properties  have  not  been  accurately  examined. 
The  number  representing  it  appears  to  be  1 30. 

Strontium  the  27th,  Calcium  the  28th,  Magnesium 
the  29th,  Siiicum  the  3Cth,  A iu??iinu7nthe  3 1st ^  Zir- 
conum  the  32d,  Glucinmn  the  33d,  and  Ittriu?n  the 
34th  of  the  undecompounded  bodies,,  like  barium,, 
have  either  not  been  procured  absolutely  pure,  or 
only  in  such  minute  quantities  that  their  properties 
are  little  known ;  they  are  formed  either  by  electrical 
powers,  or  by  the  agency  of  potassium,  from  the  dif- 
ferent earths  whose  names  they  bear,  with  the  change 
of  the  termination  in  um  ;  and  the  numbers  repre- 
senting them  are  believed  to  be  90  strontium,  40  cal- 
cium, 38  magnesium,  31  siiicum,  33  aluminum,  70 
zirconum,  39  glucinum,  1 1 1  ittrium. 

Of  the  remaining  thirteen  simple  bodies,  twelve 
are  metals,  most  of  which,  like  those  just  mentioned, 
can  only  be  procured  with  very  great  difficulty ;  and 
the  substances  in  general  from  which  they  are  proctir- 


C         46         3 

ed  are  very  rare  in  nature.  They  are  Palladium^ 
Rhodium^  Osmium^  Iridium^  Colubium^  Chromium^  Mo- 
lybdeniwiy  Cerium,  Tellurium^  Tungstenum,  Titanmn^ 
Uranium,  The  forty-seventh  body  has  not  as  yet 
been  produced  in  a  state  sufficiently  pure  to  admit 
of  a  minute  examination.  It  is  the  principle  which 
gives  character  to  the  acid  called  fluoric  acid,  and 
may  be  named  Fluon^  and  is  probably  analogous  to 
phosphorus  or  sulphur.  The  numbers  representing 
these  last  thirteen  bodies  have  not  yet  been  determin- 
ed with  sufficient  accuracy  to  render  a  reference  to 
them  of  any  utility. 

The  undecompounded  substances  unite  with  each 
other,  and  the  most  remarkable  compounds  are  form- 
ed by  the  combinations  of  oxygene  and  chlorine  with 
inflammable  bodies  and  metals  \  and  these  combina- 
tions usually  take  place  with  much  energy,  and  are 
associated  with  fire. 

Combustion  in  fact,  in  common  cases,  is  the 
process  of  the  solution  of  a  body  in  oxygene,  as  hap- 
pens when  sulphur  or  charcoal  is  burnt;  or  the  fixa- 
tion of  oxygene  by  the  combustible  body  in  a  solid 
form,  which  takes  place  when  most  metals  are  burnt, 
or  when  phosphorus  inflames  ;  or  the  production  of 
a  fluid  from  both  bodies,  as  when  hydrogene  and  oxy- 
gene unite  to  form  water. 

When  considerable  quantities  of  oxygene  or  of 
chlorine  unite  to  metals  or  inflammable  bodies,  they 
often  produce  acids  :  thus  sulphureous,  phosphoric, 
and  boracic  acids  are  formed  by  a  union  of  considera- 
ble quantities  of  oxygene  with  sulphur,  phosphorus, 


C         47  J 

and  boron  :  and  muriatic  acid  gas  is  formed  by  the 
union  of  chlorine  and  hydrogene. 

When  smaller  quantities  of  oxygene  or  chlorine 
unite  with  inflammable  bodies  or  metals,  they  form 
substances  not  acid,  and  more  or  less  soluble  in  wa- 
ter ;  and  the  metallic  oxides,  the  fixed  alkalies,  and 
the  earths,  all  bodies  connected  by  analogies  ;  are  pro- 
duced by  the  union  of  metals  with  oxygene. 

The  composition  of  any  compounds,  the  nature 
of  which  is  well  known,  may  be  easily  learnt  from  the 
numbers  representing  their  elements ;  all  that  is  ne- 
cessary, is  to  know  how  many  proportions  enter  into 
union.  Thus  potassa^  or  the  pure  caustic  vegetable 
alkali,  consists  of  one  proportion  of  potassium  and  one 
of  oxygene,  and  its  constitution  is  consequently  75 
potassium,  15  oj^ygene. 

Carbonic  acid  is  composed  of  two  proportions  of 
oxygene  30,  and  one  of  carbon  11.4. 

Again,  U?ne  consists  of  one  proportion  of  calcium 
and  one  of  oxygene,  and  it  is  composed  of  40  of  cal- 
cium and  15  of  oxygene.  And  carbonate  of  lime ^  or 
pure  chalk,  consists  of  one  proportion  of  carbonic 
acid  41.4,  and  one  of  lime  53. 

Water  consists  of  two  proportions  of  hydrogene 
2,  and  one  of  oxygene  15  ;  and  when  water  unites  to 
other  bodies  in  definite  proportions,  the  quantity  is  17, 
or  some  multiple  of  17,  i*  e,  34  or  51,  or  ^^^  &c. 

Soda^  or  the  mineral  alkali,  contains  two  propor- 
tions of  oxygene  to  one  of  sodium* 

Ammonia^  or  the  volatile  alkali  is  composed  of  six 
proportions  of  hydrogene  and  one  of  azote. 


C         48  ] 

Amongst  the  earths,  Silica  or  the  earth  of  flints, 
probably  consists  of  two  proportions  of  oxygene  to 
one  of  «ilicum  ;  and  Magnesia,  Strontia,  Baryta  or 
Barytes,  JIumina,  Zircona,  Glusina,  and  Ittria  of  one 
proportion  of  metal  and  one  of  oxygene. 

The  metallic  oxides  in  general  consist  of  the  metals 
united  to  from  one  to  four  proportions  of  oxygene ; 
and  there  are,  in  some  cases,  many  different  oxides  of 
the  same  metal  -,  thus  there  are  three  oxides  of  lead  ; 
the  yellow  oxide,  or  massicot,  contains  two  proportions 
of  oxygene  ;  the  red  oxide,  or  miniixm,  three  ;  and  the 
puse  coloured  oxide  four  proportions.  Again  there  are 
two  oxides  of  copper,  the  black  and  the  orange  ;  the 
black  contains  two  proportions  of  oxygene,  the 
orange  one. 

For  pursuing  such  experiments  on  the  composi- 
tion of  bodies  as  are  connected  with  agricultural  che- 
mistry, a  few  only  of  the  undecompounded  substan- 
ces are  necessary  ;  and  amongst  the  compounded 
bodies,  the  common  acids,  the  alkalies,  and  the  earths, 
are  the  most  essential  substances.  The  elements 
found  in  vegetables,  as  has  been  stated  in  the  intro- 
ductory lecture,  are  very  few.  Oxygene,  hydrogene, 
and  carbon  constitute  the  greatest  part  of  their  organ- 
ized matter.  Azote,  phosphorus,  sulphur,  mangane- 
sum,  iron,  silicum,  calcium,  aluminum,  and  magne- 
sium likewise,  in  different  arrangements,  enter  into 
their  composition,  or  are  found  in  the  agents  to  which 
they  are  exposed ;  and  these  twelve  undecompound- 
ed substances  are  the  elements,  the  study  of  which 
is  of  the  most  importance  to  the  agricultural  chemist. 


I         49         3 

The  doctrine  of  definite  combinations,  as  will  be 
shewn  in  the  following  lectures,  will  assist  us  in  gain- 
ing just  views  respecting  the  composition  of  plants, 
and  the  economy  of  the  vegetable  kingdom  5  but  the 
same  accuracy  of  weight  and  measure,  the  same  statical 
results  which  depend  upon  the  uniformity  of  the  laws 
that  govern  dead  matter,  cannot  be  expected  in  opera- 
tions where  the  powers  of  life  are  concerned,  and 
where  a  diversity  of  organs  and  of  functions  exists. 
The  classes  of  definite  inorganic  bodies,  even  if  we 
include  all  the  crystalline  arrangements  of  the  mineral 
kingdom,  are  few,  compared  with  the  forms  and  sub- 
stances belonging  to  animated  nature*  Life  gives  a 
peculiar  character  to  all  its  productions  j  the  power  of 
attraction  and  repulsion,  combination  and  decomposi- 
tion, are  subservient  to  it ;  a  few  elements,  by  the 
diversity  of  their  arrangement,  are  made  to  form  the 
most  different  substances ;  ajid  similar  substances  are 
produced  from  compounds  which,  when  superficially 
examined,  appear  entirely  different. 


60 


LECTURE  IIL 


On  the  Organization  of  Plants.  Of  the  Roots ^  Trunks 
and  Branches.  Of  their  Structure.  Of  the  Epider- 
mis. Of  the  cortical  and  alburnous  Parts  of  Leaves^ 
Flowers^  and  Seeds.  Of  the  chemical  Constitution  of 
the  Organs  of  Plants^  and  the  Substances  found  in 
them.  Of  mucilaginous^  saccharine^  extractive^  resin' 
cus^  and  oily.  Substances  ^  and  other  vegetable  Com* 
pounds,  their  Arrangements  in  the  Organs  of  Plants^ 
their  Composition,  Changes,  and  Uses. 

VARIETY  characterises  the  vegetable  kingdom, 
yet  there  is  an  analogy  between  the  forms  and  the 
functions  of  all  the  different  classes  of  plants,  and  on 
this  analogy  the  scientific  principles  relating  to  their 
organization  depend. 

Vegetables  are  living  structures  distinguished 
from  animals  by  exhibiting  no  signs  of  perception, 
or  of  voluntary  motion  -,  and  their  organs  are  either 
organs  of  nourishment  or  of  reproduction ;  organs 
for  the  preservation  and  increase  of  the  individual,  or 
for  the  multiplication  of  the  species. 

In  the  living  vegetable  system  there  are  to  be 
considered,  the  exterior  form,  and  the  interior  consti- 
tution. 

Every  plant  examined  as  to  external  structure, 
displays  at  least  four  systems  of  organs — or  some 
analogous  parts.     First,  the  Roof.     Secondly,   the 


C      51      3 

Trunk  and  Branches^  or  Ste?n,  Thirdly,  the  Leaves  ; 
and,  fourthly,  the  Flowers  or  Seeds, 

The  root  is  that  part  of  the  vegetable  which  least 
impresses  the  eye ;  but  it  is  absolutely  necessary.  It 
attaches  the  plant  to  the  surface,  is  its  organ  of  nour- 
ishment,  and  the  apparatus  by  which  it  imbibes  foojd 
from  the  soil. — The  roots  of  plants,  in  their  anatomi- 
cal division,  are  very  similar  to  the  trunk  and 
branches.  The  root  may  indeed  be  said  to  be  a  con- 
tinuation of  the  trunk  terminating  in  minute  ramifica- 
tions and  filaments,  and  not  in  leaves^  and  by  bury- 
ing the  branches  of  certain  trees  in  the  soil,  and  eleva- 
ting the  roots  in  the  atmospheae,  there  is,  as  it  were, 
an  inversion  of  the  functions,  the  roots  produce  buds 
and  leaves,  and  the  branches  shoot  out  into  radical 
fibres  and  tubes.  This  experiment  was  made  by 
Woodward  on  the  willow,  and  has  been  repeated  by 
a  number  of  physiologists. 

When  the  branch  or  the  root  of  a  tree  is  cut 
transversely,  it  usually  exhibits  three  bodies :  the  b^rk, 
the  wood,  and  the  pith  ;  and  these  again  are  individu- 
ally susceptible  of  a  new  division. 

The  bark,  when  perfectly  formed,  is  covered  by 
a  thin  cuticle  or  epidermis^  which  may  be  easily  separ- 
ated. It  is  generally  composed  of  a  number  of  laminae 
or  scales,  which  in  old  trees  are  usually  in  a  loose  and 
decaying  state.  The  epidermis  is  not  vascular,  and  it 
merely  defends  the  interior  parts  from  injury.  In 
forest  trees,  and  in  the  larger  shrubs,  the  bodies  of 
which  are  firm,  and  of  strong  texture,  it  is  a  part  of 
little  importance ;  but  in  the  re^ds,  the  grasses,  canes^ 


C         52         3 

and  the  plants  having  hollow  stalks,  it  is  of  great  use, 
and  is  exceedingly  strong,  and  in  the  microscope  seems 
composed  of  a  kind  of  glassy  net-work,  which  is  prin- 
cipally siliceous  earth. 

This  is  the  case  in  wheat,  in  the  oat,  in  different 
species  of  equisetum,  and,  above  all,  in  the  rattan,  the 
epidermis  of  which  contains  a  sufficient  quantity  of 
flint  to  give  light  when  struck  by  steel ;  or  two  pieces 
rubbed  together  produce  sparks.  This  fact  first  oc- 
curred to  me  in  1798,  and  it  led  to  experiments,  by 
which  I  ascertained  that  siliceous  earth  existed  gener- 
ally in  the  epidermis  of  the  hollow  plants. 

The  siliceous  epidermis  serves  as  a  support,  pro- 
tects the  bark  from  the  action  of  insects,  and  seems 
to  perform  a  part  in  the  economy  of  these  feeble  ve- 
getable tribes,  similar  to  that  performed  in  the  animal 
kingdom  by  the  shell  of  the  crustaceous  insects. 

Immediately  beneath  the  epidermis  is  the  paren- 
chyma. It  is  a  soft  substance  consisting  of  cells  filled 
with  fluid,  having  almost  always  a  greenish  tint.  The 
cells  in  the  parenchymatous  part,  when  examined  by 
the  microscope,  appear  hexagonal.  This  form,  in« 
deed,  is  that  usually  affected  by  the  cellular  mem- 
branes in  vegetables,  and  it  seems  to  be  the  result  of 
the  general  re-action  of  the  solid  parts,  similar  to  that 
which  takes  place  in  the  honey-comb.  This  arrange- 
ment, which  has  usually  been  ascribed  to  the  skill  and 
artifice  of  the  bee,  seems,  as  Dr.  Wollaston  has  ob- 
served, to  be  merely  the  result  of  the  mechanical  laws 
which  influence  the  pressure  of  cylinders  composed  of 
soft  materials,  the  nests  of  solitary  bees  being  uni- 
formly circular. 


The  innermost  part  of  the  bark  is  constituted  by 
the  cortical  layers^  and  their  numbers  vary  with  the  age 
of  the  tree.  On  cutting  the  bark  of  a  tree  of  several 
years  standing,  the  productions  of  different  periods 
may  be  distinctly  seen,  though  the  layer  of  every 
particular  year  can  seldom  be  accurately  defined. 

The  cortical  layers  are  composed  of  fibrous  parts 
which  appear  interwoven,  and  which  are  transverse 
and  longitudinal.  The  transverse  are  membranous 
and  porous,  and  the  longitudinal  are  generally  com- 
posed of  tubes. 

The  functions  of  the  parenchymatous  and  cortical 
parts  of  the  bark  are  of  great  importance.  The  tubes 
of  the  fibrous  parts  appear  to  be  the  organs  that  re- 
ceive the  sap ;  the  cells  seem  destined  for  the  elabora- 
tion of  its  parts,  and  for  the  exposure  of  them  to  the 
action  of  the  atmosphere,  and  the  new  matter  is  annu- 
ally produced  in  the  spring,  immediately  on  the  inner 
surface  of  the  cortical  layer  of  the  last  year. 

It  has  been  shewn  by  the  experiments  of  Mr. 
Knight,  and  those  made  by  other  physiologists,  that 
the  sap  descending  through  the  bark  after  being 
modified  in  the  leaves,  is  the  principal  cause  of  the 
growth  of  the  tree  ;  thus,  if  the  bark  is  wounded,  the 
principal  formation  of  new  bark  is  on  the  upper  ^dg^^ 
of  the  wound  j  and  when  the  wood  has  been  removed, 
the  formation  of  new  wood  takes  place  immediately 
beneath  the  bark :  yet  it  would  appear  from  the  late 
observations  of  M.  Palisot  de  Beauvois,  that  the  sap 
may  be  transferred  to  the  bark,  so  as  to  exert  its  nutri- 
tive functions,  independent  of  any  general  system  of 


C      54      3 

circulation.  That  gentleman  separated  different  por« 
tions  of  bark  from  the  rest  of  the  bark  in  several  trees, 
and  found  that  in  most  instances  the  separated  bark 
grew  in  the  same  manner  as  the  bark  in  its  natural 
state.  The  experiment  was  tried  with  most  success 
on  the  lime  tree,  the  maple  and  the  lilac  ;  the  layers  of 
bark  were  removed  in  August  1810,  and  in  the  spring 
of  the  next  year,  in  the  case  of  the  maple  and  the  lilac, 
small  annual  shoots  where  produced  in  the  parts 
where  the  bark  was  insulated.* 

The  wood  of  trees  is  composed  of  an  external  or 
living  part,  called  alburnum  or  sap-wood^  and  of  an  in- 
ternal and  dead  part,  the  heart-wood.  The  alburnum 
is  white,  and  full  of  moisture,  and  in  young  trees  and 
annual  shoots  it  reaches  even  to  the  pith.  The  albur- 
num is  the  great  vascular  system  of  the  vegetable 
through  which  the  sap  rises,  and  the  vessels  in  it  ex- 
tend from  the  leaves  to  the  minutest  filaments  in  the 
roots. 

There  is  in  the  alburnum  a  membranous  sub- 
stance composed  of  cells^  which  are  constantly  filled 
with  the  sap  of  the  plant,  and  there  are  in  the  vascu- 
lar system  several  different  kinds  of  tubes  ;  Mirbel  has 
distinguished  four  species,  the  simple  tubes ^  the  porous 
tubes ^  the  trachea^  and  the  false  trachea,^ 

The  tubes,  which  he  has  called  simple  tubes, 
seem  to  contain  the  resinous  or  oily  fluids  peculiar  to 
different  plants. 


•  Fig.  3  represents  the  result  of  the  experiment   on  the  maple.     Journal  de 
pLysique,  September  18U,  page  210. 

t  Fig.  4,  5,  6,  and  7,  represent  Mirbel's  idea  of  the  siipple  tubes,   the  porous 

tubes,  £l)e  tracheJe,  and  X'^t  false  tracheat. 


P    34 


Fi„.3.    I'^l 


/r^. 


rig  9 


^ 


/* 


'lilllliiimiiMr.. 


Fig:  K 


C         S5         ] 

The  porous  tubes  likewise  contain  these  fluids  ; 
and  their  use  is  probably  that  of  conveying  them  into 
the  sap  for  the  production  of  new  arrangements. 

The  tracheae  contain  fluid  matter,  which  is  al- 
ways thin,  watery,  and  pellucid,  and  these  organs, 
as  well  as  the  false  tracheae,  probably  carry  off  water 
from  the  denser  juices,  which  are  thus  enabled  to  con- 
solidate for  the  production  of  new  wood. 

In  the  arrangement  of  the  fibres  of  the  wood, 
there  are  two  distinct  appearances.  There  are  series 
of  white  and  shining  laminse  which  shoot  from  the 
centre  towards  the  circumference,  and  these  constitute 
what  is  called  the  silver  grain  of  the  wood. 

There  are  likewise  numerous  series  of  concentric 
layers  which  are  usually  called  the  spurious  grain^  and 
their  number  denotes  the  age  of  the  tree.* 

The  silver  grain  is  elastic  and  contractile,  and  it 
has  been  supposed  by  Mr.  Knight,  that  the  change  of 
volume  produced  in  it  by  change  of  temperature  is 
one  of  the  principal  causes  of  the  ascent  of  the  sap. 
The  fibres  of  it  seem  always  to  expand  in  the  morning 
and  contract  at  night ;  and  the  ascent  of  the  juices,  as 
was  stated  in  the  last  Lecture,  depends  principally  on 
the  agency  of  heat. 

The  silver  grain  is  most  distinct  in  forest  trees  ; 
but  even  annual  shrubs  have  a  system  of  fibres  simi- 
lar to  it.     The  analogy  of  nature  is  constant  and  uni- 


*  Fig.  8  represents  the  section  of  an  elm  branch,  which  exhibits  the  tubulav 
structure  and  the  silver  and  spurious  grain .  Fig.  9  represents  the  sectiou  of  part 
of  thr:  branch  of  an  oak.    Fig,  xo,  that  of  the  branch  of  an  ash. 


C      56      3 

form,  and  similar  effects  are  usually  produced  by  simi- 
lar organs. 

The  pith  occupies  the  centre  of  the  wood ;  its 
texture  is  membranous  ;  it  is  composed  of  cells,  which 
are  circular  towards  the  extremity,  and  hexagonal  iu 
the  centre  of  the  substance.  In  the  first  infancy  of 
the  vegetable,  the  pith  occupies  but  a  small  space.  It 
gradually  dilates,  and  in  annual  shoots  and  young 
trees  offers  a  considerable  diameter.  In  the  more 
advanced  age  of  the  tree,  acted  on  by  the  heart-wood, 
pressed  by  the  new  layers  of  the  alburnum,  it  begins 
to  diminish,  and  in  very  old  forest  trees  disappears 
altogether. 

Many  different  opinions  have  prevailed  with  re- 
gard to  the  use  of  the  pith.  Dr.  Hales  supposed,  that 
it  was  the  great  cause  of  the  expansion  and  develope- 
ment  of  the  other  parts  of  the  plant ;  that  being  the 
most  interior,  it  was  likewise  the  most  acted  upon  of 
all  the  organs,  and  that  from  its  reaction  the  pheno- 
mena of  their  developement  and  growth  resulted. 

Linnaeus,  whose  lively  imagination  was  continu- 
ally employed  in  endeavours  to  discover  analogies  be- 
tween the  animal  and  vegetable  systems,  conceived 
"  that  the  pith  performed  for  the  plant  the  same  func- 
tions as  the  brain  and  nerves  in  animated  beings.'*  He 
considered  it  as  the  organ  of  irritability,  and  the  seat 
of  life. 

The  latest  discoveries  have  proved,  that  these  two 
opinions  are  equally  erroneous.  Mr.  Knight  has  re- 
moved the  pith  in  several  young  trees,  and  they  con- 
tinued to  live  and  to  increase. 


t 


Fr^  JL 


I       SI       -] 

It  is  evidently  then  only  an  organ  of  secondary 
importance.  In  early  shoots,  in  vigorous  growth,  it  is 
filled  with  moisture,  and  it  is  a  reservoir,  perhaps,  of 
fluid  nourishment  at  the  time  it  is  most  wanted.  As 
the  heart^wood  forms,  it  is  more  and  more  separated 
from  the  living  part,  the  alburnum ;  its  functions  be- 
come extinct,  it  diminishes,  dies,  and  last  disap  >ears. 

The  tendrih^  the  spines^  and  other  similar  parts 
of  plants  are  analogous  in  their  organization  to  the 
branches,  and  offer  a  similar  cortical  and  alburnous 
organization.  It  has  been  shown,  by  the  late  obser- 
vations of  Mr.  Knight,  that  the  directions  of  tendrils, 
and  the  spiral  form  they  assume,  depend  upon  the 
unequal  action  of  light  upon  them,  and  a  similar 
reason  has  been  assigned  by  M.  Decandolle  to  account 
for  the  turning  of  the  parts  of  plants  towards  the  sun ; 
that  ingenious  physiologist  supposes  that  the  fibres 
are  shortened  by  the  chemical  agency  of  the  solar 
rays  upon  them,  and  that,  consequently,  the  parts 
will  move  towards  the  light. 

The  leaves  J  the  great  sources  of  the  permanent 
beauty  of  vegetation,  though  infinitely  diversified  in 
their  forms,  are  in  all  cases  similar  in  interior  organi- 
zation, and  perform  the  same  functions. 

The  alburnum  spreads  itself  from  the  foot-stalks 
into  the  very  extremity  of  the  leaf )  it  retains  its  vas- 
cular system  and  its  living  powers  ;  and  its  peculiar 
tubes,  particularly  the  tracheae,  may  be  distinctly  seen 
in  the  leaf.* 


•  Fig  11.  represents  part  of  a  leaf  of  a  vine  magnified  and  cut,  so  as  to  exhi- 
bit the  trachea  ;  it  is  copied,  as  are  also  the  preceding  figures,  from  Grew's  Ani- 
.tomy  of  Plants. 


[  58  ] 

The  green  membranous  substance  may  be  consi- 
dered as  an  extension  of  the  parenchyma,  and  the 
fine  and  thin  covering  as  the  epidermis.  Thus  the 
organization  of  the  roots  and  branches  may  be  traced 
into  the  leaves,  which  present,  however,  a  more  per- 
fect, refined,  and  minute  structure. 

One  great  use  of  the  leaves  is,  for  the  exposure 
of  the  sap  to  the  influence  of  the  air,  heat,  and  light. 
Their  surface  is  extensive,  the  tubes  and  cells 
very  delicate,  and  their  texture  porous  and  trans- 
parent. 

In  the  leaves  much  of  the  water  of  the  sap  is 
evaporated  ;  it  is  combined  with  new  principles,  and 
fitted  for  its  organizing  functions,  and  probably  pas- 
ses, in  its  prepared  state,  from  the  extreme  tubes  of 
the  alburnum  into  the  ramifications  of  the  cortical 
tubes  and  then  descends  through  the  bark. 

On  the  upper  surface  of  leaves,  which  is  expos- 
ed to  the  sun,  the  epidermis  is  thick  but  transparent, 
and  is  composed  of  matter  possessed  of  little  organi- 
zation, which  is  either  principally  earthy,  or  consists 
of  some  homogeneous  chemical  substance.  In  the 
grasses  it  is  partly  siliceous,  in  the  laurel  resinous, 
and  in  the  maple  and  thorn,  it  is  principally  constitut- 
ed by  a  substance  analogous  to  wax. 

By  these  arrangements  any  evaporation,  except 
from  the  appropriated  tubes,  is  prevented. 

On  the  lower  surface  the  epidermis  is  a  thin 
transparent  membrane  full  of  cavities,  and  it  is  proba- 
bly altogether  by  this  surface  that  moisture  and  the 
principles  of  the  atmosphere  necessary  to  vegetation 
are  absorbed. 


C         59         ] 

If  a  leaf  be  turned,  so  as  to  present  its  lower  sur- 
face to  the  sun,  its  fibres  will  twist  so  as  to  bring  it  as 
much  as  possible  into  its  original  position  j  and  all 
leaves  elevate  themselves  on  the  foot-stalk  during  their 
exposure  to  the  solar  light,  and  as  it  were  moved  to- 
wards  the  sun. 

This  effect  seems  in  a  great  measure  dependent 
upon  the  mechanical  and  chemical  agency  of  light  and 
heat.  Bonnet  made  artificial  leaves,  which,  when  a 
moist  sponge  was  held  under  the  lower  surface,  and 
a  heated  iron  above  the  upper  surface,  turned  exactly 
in  the  same  manner  as  the  natural  leaves.  This  how- 
ever can  be  considered  only  as  a  very  rude  imitation 
of  the  natural  process. 

What  Linnaeus  has  called  the  sleep  of  the  leaves, 
appears  to  depend  wholly  upon  the  defect  of  the  ac- 
tion of  light  and  heat,  and  the  excess  of  the  operation 
of  moisture. 

This  singular  but  constant  phenomenon  had 
never  been  scientifically  observed,  till  the  attention  of 
the  botanist  of  Upsal  was  fortunately  directed  to  it. 
He  was  examining  particularly  a  species  of  lotus,  in 
which  four  flowers  had  appeared  during  the  day,  and 
he  missed  two  in  the  evening ;  by  accurate  inspection, 
he  soon  discovered  that  these  two  were  hidden  by  the 
leaves  which  had  closed  round  them.  Such  a  circum- 
stance could  not  be  lost  upon  so  acute  an  observer* 
He  immediately  took  a  lantern,  went  into  his  garden, 
and  witnessed  a  series  of  curious  facts  before  un- 
known. All  the  simple  leaves  of  the  plants  he  exam- 
ined, had  an  arrangement  totally  different  from  their 


[         60        3 

arrangement  in  the  day  :  and  the  greater  number  of 
them  were  seen  closed  or  folded  together. 

The  sleep  of  leaves  is,  in  some  cases,  capable  of 
being  produced  artificially.  Decandoile  made  this  ex- 
periment on  the  sensitive  plant.  By  confining  it  in 
a  dark  place  in  the  day  time,  the  leaves  soon  closed ; 
but  on  illuminating  the  chamber  with  many  lamps, 
they  again  expanded.  So  sensible  were  they  to  the 
effects  of  light  and  radiant  heat. 

In  the  greater  number  of  plants  the  leaves  annu- 
ally decay,  and  are  reproduced  ;  their  decay  takes  place 
either  at  the  conclusion  of  the  summer,  as  in  very  hot 
climates,  when  they  are  no  longer  supplied  with  sap, 
in  consequence  of  the  dryness  of  the  soil,  and  the 
evaporating  powers  of  heat  j  or  in  the  autumn,  as  in 
the  northern  cHmates  at  the  commencement  of  the 
''frosts.  The  leaves  preserve  their  functions  in  com- 
mon cases  no  longer  than  there  is  a  circulation  of 
fluids  through  them.  In  the  decay  of  the  leaf,  the 
colour  assumed  seems  to  depend  upon  the  nature  of 
the  chemical  change,  and  as  acids  are  generally  devel- 
oped, it  is  usually  either  reddish  brown  or  yellow ; 
yet  there  are  great  varieties.  Thus  in  the  oak,  it  is 
bright  brown  ;  in  the  beech,  orange  ;  in  the  elm,  yel- 
low 'y  in  the  vine,  red ;  in  the  sycamore,  dark  brown  ^ 
in  the  cornel  tree,  purple  ;  and  in  the  woodbine,  blue. 

The  cause  of  the  preservation  of  the  leaves  of 
evergreens  through  the  winter  is  not  accurately 
known.  From  the  experiments  of  Hales,  it  appears 
that  the  force  of  the  sap  is  much  less  in  plants  of  this 
species,  and  probably  there  is  a  certain  degree  of  circu- 


C      61       3 

lation  throughout  the  winter ;  their  juices  are  less  wa- 
tery than  those  of  other  plants,  and  probably  less  liable 
to  be  congealed  by  cold,  and  they  are  defended 
by  stronger  coatings  from  the  action  of  the 
elements. 

The  production  of  the  other  parts  of  the  plant 
takes  place  at  the  time  the  leaves  are  most  vigorously 
performing  their  functions.  If  the  leaves  are  stripped 
off  from  a  tree  in  spring,  it  uniformly  dies,  and  when 
many  of  the  leaves  of  forest  trees  are  injured  by 
blasts,  the  trees  always  become  stag-headed  and  un- 
healthy. 

The  leaves  are  necessary  for  the  existence  of  the 
individual  tree,  the  flowers  for  the  continuance  of  the 
species.  Of  all  the  parts  of  plants  they  are  the  most 
refined,  the  most  beautiful  in  their  structure,  and  ap- 
pear as  the  master-work  of  nature  in  the  vegetable 
kingdom.  The  elegance  of  their  tints,  the  variety  of 
their  forms,  the  delicacy  of  their  organization,  and 
the  adaptation  of  their  parts,  are  all  calculated  to 
awaken  our  curiosity,  and  excite  our  admiration. 

In  the  flower  there  are  to  be  observed,  1st,  the 
calyx^  or  green  membranous  part  forming  the  support 
for  the  coloured  floral  leaves.  This  is  vascular,  and 
agrees  with  the  common  leaf  in  its  texture  and  organi- 
zation ;  it  defends,  supports,  and  nourishes  the  more 
perfect  parts.  2d.  The  corolla,  which  consists  either 
of  a  single  piece,  when  it  is  called  monopetalous,  or  of 
many  pieces,  when  it  is  called  polypetalous.  It  is 
usually  very  vivid  in  its  colours,  is  filled  with  an  al- 
most infinite  variety  of  small  tubes  of  the  porous  kind  5 


C         63         ] 

it  incloses  and  defends  the  essential  parts  in  the  inte- 
rior, and  supplies  the  juices  of  the  sap  to  them.  These 
parts  are,  3d,  the  stamens  and  the  pistils. 

The  essential  part  of  the  stamens  are  the  sum- 
mits or  anthers^  which  are  usually  circular  and  of  a 
highly  vascular  texture,  and  covered  with  a  fine  dust 
called  the  pollen. 

The  pistil  is  cylindrical,  and  surmounted  by  the 
style  ;  and  top  of  which  is  generally  round  and  pro- 
tuberant.* 

In  the  pistil,  when  it  is  examined  by  the  micro- 
scope, congeries  of  spherical  forms  may  usually  be 
perceived,  which  seem  to  be  the  bases  of  the  future 
seeds. 

It  is  upon  the  arrangement  of  the  stamens  and 
the  pistils,  that  the  Linnean  classification  is  founded. 
The  numbers  of  the  stamens  and  pistils  in  the  same 
flower,  their  arrangements,  or  their  division  in  differ- 
ent flowers,  are  the  circumstances  which  guided  the 
Swedish  philosopher,  and  enabled  him  to  form  a  sys- 
tem admirably  adapted  to  assist  the  memory,  and  ren- 
der  botany  of  easy  acquisition ;  and  which,  though  it 
does  not  always  associate  together  the  plants  most 
analogous  to  each  other  in  their  general  characters,  is 
yet  so  ingeniously  contrived  as  to  denote  all  the  analo- 
gies of  their  most  essential  parts. 

The  pisdl  is  the  organ  which  contains  the  rudi- 
ments of  the  seed  ;  but  the  seed  is  never  formed  as  a 


*  Fig.  12  represents  the  common  lilly»  a,  the  corolla,    bbbbb,  the  anthors/ 
c,  the  pistil. 


reproductive  germ,  without  the  influence  of  the  pollen, 
or  dust  on  the  anthers. 

This  mysterious  impression  is  necessary  to  the 
continued  succession  of  the  different  vegetable  tribes. 
It  is  a  feature  \vhich  extends  the  resemblances  of  the 
different  orders  of  beings,  and  establishes,  on  a  great 
scale,  the  beautiful  analogy  of  nature. 

The  ancients  had  observed,  that  different  date 
trees  bore  different  flowers,  and  that  those  trees  pro- 
ducing flowers  which  contained  pistils  bore  no  fruit, 
unless  in  the  immediate  vicinity  of  such  trees  as  pro^ 
duced  flowers  containing  stamens.  This  long  esta- 
blished fact  strongly  impressed  the  mind  of  Malpighi, 
who  ascertained  several  analogous  facts  with  regard  to 
other  vegetables.  Grew,  however,  was  the  first  per- 
son who  attempted  to  generalize  upon  them,  and 
much  just  reasoning  on  the  subject  may  be  found  in 
his  works.  Linnaeus  gave  a  scientific  and  distinct 
form  to  that  which  Grew  had  only  generally  observ- 
ed, and  has  the  glory  of  establishing  what  has  been 
called  the  sexual  system,  upon  the  basis  of  minute  ob- 
servations and  accurate  experiments. 

The  seedy  the  last  production  of  vigorous  vegeta- 
tion, is  wonderfully  diversified  in  form.  Being  of  the 
highest  importance  to  the  resources  of  nature,  it  is 
defended  above  all  other  parts  of  the  plant ;  by  soft 
pulpy  substances,  as  in  the  esculent  fruits,  by  thick 
membranes,  as  in  the  leguminous  vegetables,  and  by 
hard  shells,  or  a  thick  epidermis,  as  in  the  palms  and 
grasses. 


K  . 


C         6*         1 

In  every  seed  there  is  to  be  distinguished,  1,  the 
organ  of  nourishment ;  2,  the  nascent  plant,  or  the 
flujiie  ;  3,  the  nascent  root,  or  the  radicle. 

In  the  common  garden  bean,  the  organ  of  nour- 
ishment is  divided  into  two  lobes  called  cotyledons  ;  the 
plume  is  the  small  white  point  between  the  upper 
part  of  the  lobes  ;  and  the  radicle  is  the  small  curved 
cone  at  their  base.* 

In  wheat,  and  in  many  of  the  grasses,  the  organ 
of  nourishment  is  a  single  part,  and  these  plants  are 
called  monocotyledonous*  In  other  cases  it  consists  of 
more  than  two  parts,  when  the  plants  are  called  poly- 
cotyledonous.  In  the  greater  number  of  instances,  it 
is,  however,  simply  divided  into  two,  and  is  dicotyle- 
donous. 

The  matter  of  the  seed,  when  examined  in  its 
common  state,  appears  dead  and  inert ;  it  exhibits 
neither  the  forms  nor  the  functions  of  life.  But  let 
it  be  acted  upon  by  moisture,  heat,  and  air,  and  its 
organized  powers  are  soon  distinctly  developed.  The 
cotyledons  expand,  the  membranes  burst,  the  radicle 
acquires  new  matter,  descends  into  the  soil,  and  the 
pUime  rises  towards  the  free  air.  By  degrees,  the 
organs  of  nourishment  of  dicotyledonous  plants  be- 
come vascular,  and  are  converted  into  seed  leaves, 
and  the  perfect  plant  appears  above  the  soil.  Nature 
has  provided  the  elements  of  germination  on  every 
part  of  the  surface ;  water  and  pure  air  and  heat  are 


•  Fig.  13,  represents  the  garden  bean,  aa,  the  cotyledons,  b,  the  plume,  b,  the 

radicle. 


p.  64 


0;;f'^rfi 


fiq.  12. 


^^ 


% 


■m 


f^%l 


'^M 


universally  active,  and  the  means  for  the  preserva- 
tion and  muhiplication  of  life,  are  at  once  simple  and 
grand. 

To  enter  into  more  minute  details  on  the  vegetable 
physiology  would  be  incompatible  with  the  objects  of 
these  Lectures.  I  have  attempted  only  to  give  such 
general  ideas  on  the  subject,  as  may  enable  the  philo- 
sophical agriculturist  to  understand  the  functions  of 
plants  ;  those  who  wish  to  study  the  anatomy  of  ve- 
getables, as  a  distinct  science,  will  find  abundant  ma- 
terials in  the  works  of  the  authors  I  have  quoted, 
page  9,  and  likewise  in  the  writings  of  Linnaeus,  Des- 
fontaines,  Decandolle,  de  Saussure,  Bonnet,  and' 
Smith. 

The  history  of  the  p  eculiarities  of  structure  in  the 
different  vegetable  classes,  rather  belongs  to  botanical 
than  agricultural  knowledge.  As  I  mentioned  in  the 
commencement  of  this  Lecture,  their  organs  are  pos- 
sessed of  the  most  distinct  analogies,  and  are  govern- 
ed by  the  same  laws.  In  the  grasses  and  palms,  the 
cortical  layers  are  larger  in  proportion  than  the  other 
parts  ;  but  their  uses  seem  to  be  the  same  as  in  forest 
trees. 

In  bulbous  roots,  the  alburnous  substance  forms 
the  largest  part  of  the  vegetable  ;  but  in  all  cases  it 
seems  to  contain  the  sap,  or  solid  materials  deposited 
from  the  sap. 

The  slender  and  comparatively  dry  leaves  of  the 
pine  and  the  cedar  perform  the  same  functions  as  the 
large  and  juicy  leaves  of  the  fig  tree,  or  the  walhut 

K 


[         66         ] 

Even  in  the  cryptogamia,  where  no  flowers  are 
distinct,  still  there  is  every  reason  to  believe  that  the 
production  of  the  seed  is  effected  in  the  same  way  as 
in  the  more  perfect  plants.  The  mosses  and  lichens, 
which  belong  to  this  family,  have  no  distinct  leaves, 
or  roots,  but  they  are  furnished  with  filaments  which 
perform  the  same  functions  ;  ^nd  even  in  the  fungus 
and  the  mushroom  there  is  a  system  for  the  absorp- 
tion and  aeration  of  the  sap. 

It  was  stated  in  the  last  lecture,  that  all  the  differ- 
ent parts  of  plants  are  capable  of  being  decomposed 
into  a  few  elements.  Their  uses  as  food,  or  for  the 
purposes  of  the  arts,  depend  upon  compound  arrange- 
ments of  those  elements  which  are  capable  of  being 
produced  either  from  their  organized  parts,  or  from 
the  juices  they  contain  ;  and  the  examination  of  the 
nature  of  these  substances,  is  an  essential  part  of  Agri- 
cultural Chemistry. 

Oils  are  expressed  from  the  fruits  of  many 
plants  'y  resinous  fluids  exude  from  the  wood  ;  sac- 
charine matters  are  afforded  by  the  sap ;  and  dyeing 
materials  are  furnished  by  leaves,  or  the  petals  of 
flowers  :  but  particular  processes  are  necessary  to  se- 
parate the  different  compound  vegetable  substances 
from  each  other,  such  as  maceration,  infusion  or  diges- 
tion in  water,  or  in  spirits  of  wine  :  but  the  application 
and  the  nature  of  these  processes  will  be  better  under- 
stood when  the  chemical  nature  of  the  substances  is 
known  ;  the  consideration  of  them  will  therefore  be 
reserved  for  another  place  in  this  Lecture. 


[         67         ] 

llie  compound  substances  found  in  vegetables 
are,  1  gum,  or  mucilage,  and  its  different  modifica- 
tions ;  2,  starch  j  3,  sugar  ;  4,  albumen  ;  5,  gluten  ; 
6,  gum  elastic  ;  7,  extract ;  8,  tannin  ;  9,  indigo  j 
10,  narcotic  principle  ;  11,  bitter  principle  j  12,  wax  ; 
13,  resins  ;  14,  camphor  ;  15,  fixed  oils  ;  16,  vola- 
tile oils  5  17,  woody  fibre  ;  18,  acids  ;  19,  alkalies  y 
earths,  metallic  oxides,  and  saline  compounds. 

I  shall  describe  generally  the  properties  and 
composition  of  these  bodies,  and  the  manner  in  which 
they  are  procured. 

1.  Gu??i  is  a  substance  which  exudes  from  certain 
trees  ;  it  appears  in  the  form  of  a  thick  fluid,  but  soon 
hardens  in  the  air,  and  becomes  solid  :  when  it  is 
white,  or  yellowish  white,  more  or  less  transparent, 
and  somewhat  brittle  5  its  specific  gravity  varies  from 
1300  to  1490. 

There  is  a  great  variety  of  gums,  but  the  best 
know  are  gum  arable,  gum  Senegal,  gum  tragacanth, 
and  the  gum  of  the  plum  or  cherry  tree.  Gum  is 
soluble  in  v/ater,  but  not  soluble  in  spirits  of  wine.  If 
a  solution  of  gum  be  made  in  water,  and  spirits  of 
wine  or  alcohol  be  added  to  it,  the  gum  separates  in 
the  form  of  white  flakes.  Gum  can  be  made  to  in- 
flame only  with  difficulty  ;  much  moisture  is  given  off 
in  the  process,  which  takes  place  with  a  dark  smoke 
and  feeble  blue  flame,  and  a  coal  remains. 

The  characteristic  properties  of  gum  are  its  easy 
solubility  in  water,  and  its  insolubility  in  alcohol.  Dif- 
ferent chemical  substances  have  been  proposed  for 
ascertaining  the  presence  of  gum,  but  there  is  reason 


C         68         3 

to  believe  that  few  of  them  afford  accurate  results  ;  and 
most  of  them  (particularly  the  metallic  salts,)  which 
produce  changes  in  solutions  of  gum,  may  be  conceiv- 
ed to  act  rather  upon  some  saline  compounds  existing 
in  the  gum,  than  upon  the  pure  vegetable  principle. 
Dr.  Thomson  has  proposed  an  aqueous  solution  of 
silica  in  potassa  as  a  test  of  the  presence  of  gum  in 
solutions — he  states  that  the  gum  and  silica  are  pre- 
cipitated together — this  test,  however,  cannot  be  ap- 
plied with  correct  results  in  cases  when  acids  are 
present. 

Mucilage  must  be  considered  as  a  variety  of  gum; 
it  agrees  with  it  in  its  most  important  properties,  but 
seems  to  have  less  attraction  for  water. — According 
to  Hermbstadt,  when  gum  and  mucilage  are  dissolved 
together  in  water,  the  mucilage  may  be  separated  by 
means  of  sulphuric  acid — mucilage  may  be  procured 
from  linseed,  from  the  bulbs  of  the  hyacinth,  from 
the  leaves  of  the  marsh-mallows  ;  from  several  of  the 
lichens,  and  from  many  other  vegetable  substances. 

From  the  analysis  of  M.  M.  Gay  Lussac  and 
Thenard,  it  appears  that  gum  arabic  contains  in  100 
parts : 

of  carbon        -         -         .         -         42,23 

—  oxygene     -         -         -         -         50,84? 

—  hydrogene  -         -         -  6,93 
with  a  small  quantity  of  saline  and  earthy  matter. 


or  of  carbon  •        .        -        42,23 

oxygene  and  hydrogene  in  the  pro- 1     ^^  >7<^ 

portions  necessary  to  form  water  J        ' 


C         69         ] 

This  estimation  agrees  very  nearly  with  the  definite 
proportions  of  11  of  carbon,  10  of  oxygene,  and  20 
of  hydrogene. 

All  the  varieties  of  gum  and  mucilage  are  nutri- 
tious as  food.  They  either  partially  or  wholly  lose 
their  solubility  in  water  by  being  exposed  to  a  heat 
of  500"  or  600°  Fahrenheit,  but  their  nutritive  powers 
are  not  destroyed  unless  they  are  decomposed.  Gum 
and  mucilage  are  employed  in  some  of  the  arts,  parti- 
cularly in  calico-printing  :  till  lately.  In  this  country, 
the  calico-printers  used  gum  arable  ;  but  many  of 
them,  at  the  suggestion  of  Lord  Dundonald,  now 
employ  the  mucilage  from  lichens. 

2.  Starch  is  procured  from  different  vegetables, 
but  particularly  from  wheat  or  from  potatoes.  To 
make  starch  from  wheat,  the  grain  is  steeped  in  cold 
water  till  it  becomes  soft,  and  yields  a  milky  juice  by 
pressure  ;  it  is  then  put  into  sacks  of  linen,  and  pres- 
sed in  a  vat  filled  with  water :  as  long  as  any  milky 
juice  exudes  the  pressure  is  continued ;  the  fluid 
gradually  becomes  clear,  and  a  white  powder  subsides, 
which  is  starch. 

Starch  is  soluble  in  boiling  water,  but  not  in 
cold  water,  nor  in  spirits  of  wine.  According  to 
Dr.  Thomson,  it  is  a  characteristic  property  of  starch 
to  be  soluble  in  a  warm  infusion  of  nutgalls,  and  to 
form  a  precipitate  when  the  infusion  cools. 

Starch  is  more  readily  combustible  than  gum  j 
when  thrown  upon  red  hot  iron,  it  burns  with  a  kind 
of  explosion,  and   scarcely  any  residuum  remains. 


i:     TO    j 

According   to  Mr.  Gay  Lussac  and  Thenard,  100 
parts  of  starch  are  composed  of 

Carbon,  with  a  small  quantity  of  1 

salme  and  earthy  matter      -       J  ' 

^     Oxygene          -         -         .         .  49,68 

Hydrogene      -         -         -         -  6,77 


or. 


Carbon  -         -         -         .         43,55 

Oxygene  and   hydrogene  in  the"| 
proportions  necessary    to  form  r*    56,45 
water  u         -         .         .  j 

Supposing  this  estimation  correct,  starch  may  be 
conceived  to  be  constituted  by  1 5  proportions  of  car- 
bon, 1 3  of  oxygene,  and  26  of  hydrogene. 

Starch  forms  a  principal  part  of  a  number  of  es- 
culent vegetable  substances.  Sowans,  cassava,  salop, 
sago,  all  of  them  owe  their  nutritive  powers  principal- 
ly to  the  starch  they  contain. 

Starch  has  been  found  in  the  following  plants : 

Burdock  (Arctium  Lappa^J  Deadly  Nightshade 
( Atropa  Belladonna^)  Bistort  (Polygonum  Bisiorfa^J 
White  Bryony  (Bryonia  alba^)  Meadow  Saffron  (Col- 
chicuni  autumnale^)  Drop  wort  (Spiraa  Filipendula^) 
^Mliercw^  (Ranunculus  bulbosus^  J  Figwort  (  Scrophu- 
laria  nodosa^)  Dwarf  Elder  (Sambucus  Ebulus^J  Com- 
mon Elder  (Sa??ibucus  nigra,  J  Foolstones  (Orchis  Mo* 
rio,J  Alexanders  (Imperatoria  Ostruthium,)  Henbane 
(Hyoscyamus  niger,)  Broad-leaved  Dock  (  Rumex  obtu- 
sifolius,)  Sharp  Pointed  Dock  {Rumex  acutus,)  Water 
Dock  (Rumex  acquaticus^  Wake  Robin  {Arum  macu- 


C      -71       3 

latum^  Salep  (Orchis  masciila^  Flower  de  luce,  or 
Water  Flag  {Iris  Fseudacorus^  Stinking  Gladwyn  {Iris 
fxtidissijna^)  Earthnut  {Bunium  Bulbopastanu?n,) 

3.  Sugar  in  its  purest  state  is  prepared  from  the 
expressed  juice  of  the  Saccharum  Officinarum,  or  sugar 
cane  ;  the  acid  in  this  juice  is  neutralized  by  lime, 
and  the  sugar  is  crystallized  by  the  evaporation  of  the 
aqueous  parts  of  the  juice,  and  slow-cooling :  it  is 
rendered  white  by  the  gradual  filtration  of  water 
through  it.  In  the  common  process  of  manufacture, 
the  whitening  or  refining  of  sugar  is  only  affected  in  a 
great  length  of  time  ;  the  water  being  gradually  suf- 
fered to  percolate  through  a  stratum  of  clay  above  the 
sugar.  As  the  colouring  matter  of  sugar  is  soluble 
in  a  saturated  solution  of  sugar,  or  syrup,  it  appears 
that  refining  may  be  much  more  rapidly  and  oecono- 
mically  performed  by  the  action  of  syrup  on  coloured 
sugar.*  The  sensible  properties  of  sugar  are  well 
known.  Its  specific  gravity  according  to  Fahrenheit 
is  about  1.6.  It  is  soluble  in  its  own  weight  of  water 
at  50° ;  it  is  likewise  soluble  in  alcohol,  but  in  smal- 
ler proportions. 


*  A  French  gentleman  lately  in  this  country  (England),  stated  to  the  West 
India  planters,  that  he  was  in  possession  of  a  very  expeditious  and  economical 
method  of  purifying  and  refining  sugar,  which  he  was  willing  to  communicate  to 
them  for  a  very  great  pecuniary  compensation.  His  terms  were  too  high  to  be 
acceded  to.  Conversing  on  the  subject  with  Sir  Joseph  Banks,  I  mentioned  to 
him,  that  I  thought  it  probable  that  raw  sugar  might  be  easily  purified  by  passing 
syrup  through  it,  which  would  dissolve  the  colouring  matter.  The  same  idea 
seems  to  have  occurred  about  the  same  time,  or  before,  to  Edward  Howard,  Esq, 
who  has  since  proved  its  efficacy  experimentally,  and  has  published  an  account  of 
his  process. 


C         72         3 

Lavoisier  concluded  from  his  experiments,  that 
sugar  consists  in  100  parts  of 
28  carbon, 

8  hydrogene, 
64  ox\  gene. 
Dr.  Thomson  considers  100  parts  of  sugar  as 
composed  of  ^    27,5  carbon, 

7,8  hydrogene, 
64,7  oxygene. 
According   to  the  recent  experiments  of  Gay 
Lussac  and  Thenard,  sugar  consists  of 
42,47  of  carbon,  and 
57,53  of  water,  or  its  elements. 
Lavoisier's  and  Dr.  Thomson's  analyses   agree 
very  nearly  with  the  proportions  of 

3  of  carbon, 

4  of  oxygene,  and 
8  of  hydrogene. 

Gay  Lussac's  and  Thenard's  estimation  gives  the 
same  elements  as  in  gum  ;  1 1  of  carbon,  10  of  oxy- 
gene, 20  of  hydrogene. 

It  appears  from  the  experiments  of  Proust,  Ach- 
ard,  Goettling  and  Parmentier,  that  there  are  many 
diiFerent  species  of  sugar  ready  formed  in  the  vegeta- 
ble kingdom.  The  sugar  which  most  nearly  resem- 
bles that  of  the  cane  is  extracted  from  the  sap  of  the 
American  maple,  Acer  saccharinum.  This  sugar  is  used 
by  the  North  American  farmers,  who  procure  it  by  a 
kind  of  domestic  manufacture.  The  trunk  of  the  tree 
is  bored  early  in  spring,  to  the  depth  of  about  two  in- 
ches ;  a  wooden  spout  is  introduced  into  the  hole  ;  the 


C         73         1 

juice  flows  for  about  five  or  six  weeks.  A  common 
sized  tree,  that  is,  a  tree  from  two  to  three  feet  in 
diameter,  will  yield  about  200  pints  of  sap,  and  every 
40  pints  of  sap  afford  about  a  pound  of  sugar.  The 
sap  is  neutralized  by  lime,  and  deposits  crystals  of 
sugar  by  evaporation. 

Tli^  sugar  of  grapes  has  been  lately  employed  in 
France  as  a  substitute  for  colonial  sugar.  It  is  pro- 
cured from  the  juice  of  ripe  grapes  by  evaporation,  and 
the  action  of  pot-ashes  ;  it  is  less  sweet  than  common 
sugar,  and  its  taste  is  peculiar  :  it  produces  a  sensa- 
tion of  cold  while  dissolving  in  the  mouth  ^  and  it  is 
probable  contains  a  larger  proportion  of  water  or  its 
elements. 

The  roots  of  the  beet  (Beta  vulgaris  and  cicla^ 
afford  a  peculiar  sugar,  by  boiling,  and  the  evapora- 
tion of  the  extract :  it  agrees  in  its  general  properties 
with  the  sugar  of  grapes,  but  has  a  slightly  bitter 
taste. 

Manna^  a  substance  which  exudes  from  various 
trees,  particularly  from  the  Fraxinus  Ornus,  2l  species 
of  ash,  which  grows  abundantly  in  Sicily  and  Calabria, 
may  be  regarded  as  a  variety  of  sugar,  very  analo- 
gous to  the  sugar  of  grapes.  A  substance  analogous 
to  manna  has  been  extracted  by  Fourcroy  and  Vau- 
quelin,  from  the  juice  of  the  common  onion  (Allium 
Cepa.) 

Besides  the  crystallized  and  solid  sugars,  there 
appears  to  be  a  sugar  which  cannot  be  separated  from 
water,  and  which  exists  only  in  a  fluid  form  ;  it  con- 
stitutes a  principal  part  of  melasses  or  treacle  j  and  it 

L 


L        V*        J 

is  found  in  a  variety  of  fruits  :  it  is  more  soluble  in 
alcohol  than  solid  sugar. 

The  simplest  mode  of  detecting  sugar  is  that  re- 
commended by  Margraaf.  The  vegetable  is  to  be 
boiled  in  a  small  quantity  of  alcohol ;  solid  sugar,  if 
any  exist,  will  separate  during  the  cooling  of  the  solu- 
tion. 

Sugar  has  been  extracted  from  the  following  ve- 
getable substances. 

The  sap  of  the  Birch  (Betula  alba,)  of  the  Sy- 
camore (^Acer  Pseudoplatanus,^  of  the  Bamboo  {Ar un- 
do Bambos,)  of  the  Maize  (^Zea  inays,)  of  the  Cow 
Parsnip  (Heraclewn  Spbondylium,)  of  the  Cocoa-nut 
tree  (Cocos  nucifera,)  of  the  Walnut  tree  (Juglans 
alba,)  of  the  American  Aloe  (Agave  mericana,')  of  the 
Dulse  (Fucus  Pahnatus^  of  the  Common  Parsnip 
(Pastinica  sativa,)  of  St.  John's  bread  (Ceratonia  Sili^ 
qua,)  the  fruit  of  the  common  Arbutus  {Arbutus 
Unedo,)  and  other  sweet-tasted  fruits  ;  the  roots  of 
the  turnip  (Brassica  Rapa,)  of  the  carrot  (Daucus  Car- 
Ota,)  of  Parsley  (Apium  Petroselinum,)  the  flower  of 
the  Euxine  Rhododendron  {Rhododendron  poniicum^) 
and  from  the  nectarium  of  most  other  flowers. 

The  nutritive  properties  of  sugar  are  well  known. 
Since  the  British  market  has  been  over-stocked  with 
this  article  from  the  West  India,  islands,  proposals 
have  been  made  for  applying  it  as  the  food  of  cattle ; 
experiments  have  been  made  which  proved  that  they 
may  be  fattened  by  it ;  but  difficulties  connected  with 
the  duties  laid  on  sugar,  have  hitherto  prevented  the 
plan  from  being  tried  to  any  extent. 


L'      "5      3 

4.  Albumen  Is  a  substance  which  has  only  lately 
been  discovered  in  the  vegetable  kingdom.  It  abounds 
in  the  juice  of  the  papaw-tree  (Car tea  papaya)  :  when 
this  juice  is  boiled  the  albumen  falls  down  in  a  coagu- 
lated state.  It  is  likewise  found  in  mushrooms,  and 
in  different  species  of  funguses. 

Albumen  in  its  pure  form,  is  a  thick,  glairy,  taste- 
less fluid ;  precisely  the  same  as  the  white  of  the  egg ;  it 
is  soluble  in  cold  water  ;  its  solution,  when  not  too  di- 
luted, is  coagulated  by  boiling,  and  the  albumen  separ- 
ates in  the  form  of  thin  flakes.  Albumen  is  likewise 
coagulated  by  acids  atid  by  alcohol :  a  solution  of  al- 
bumen gives  a  precipitate  when  mixed  with  a  cold 
solution  of  nut-galls.  Albumen  when  burnt  produces 
a  smell  of  volatile  alkali,  and  affords  carbonic  acid  and 
water  ;  it  is  therefore  evidently  principally  composed 
of  carbon,  hydrogene,  oxygene,  and  azote. 

According  to  the  experiments  of  Gay  Lussac  and 
Thenard,  100  parts  of  albumen  from  the  white  of  the 
egg  are  composed  of 

Carbon  -  *  52,883 

Oxygene  -  -  23,872 

Hydrogene  -  -  7,540 

Azote     -  .  -  15,705 

This  estimation  would  authorise  the  supposition, 
that  albumen  is  composed  of  2  proportions  of  azote, 
5  oxygene,  9  carbon,  22  hydrogene* 

The  principal  part  of  the  almond,  and  of  the 
kernels  of  many  other  nuts,  appears  from  the  experi- 
ments of  Proust,  to  be  a  substance  analogous  to  co- 
agulated albumen. 


'     f      I        76        ] 

The  juice  of  the  fruit  of  the  Ochra  (Hibiscus 
escukntus),  according  to  Dr.  Clarke,  contains  a  liquid 
albumen  in  such  quantities,  that  it  is  employed  in 
Dominica  as  a  substitute  for  the  white  of  eggs  in  clari- 
fying the  juice  of  the  sugar  cane. 

Albumen  may  be  distinguished  from  other  sub- 
stances by  its  property  of  coagulating  by  the  action  of 
heat  or  acids,  when  dissolved  in  water.  According 
to  Dr.  Bostock,  when  the  solution  contains  only  one 
grain  of  albumen  to  1000  grains  of  water,  it  becomes 
cloudy  by  being  heated. 

Albumen  is  a  substance  common  to  the  animal 
as  well  as  to  the  vegetable  kingdom,  and  much  more 
abundant  in  the  former. 

3.  Gluten  may  be  obtained  from  wheaten  flour  by 
the  following  process  :  the  flour  is  to  be  made  into  a 
paste,  which  is  to  be  cautiously  washed,  by  kneading 
it  under  a  small  stream  of  water,  till  the  water  has 
carried  off  from  it  all  the  starch ;  what  remains  is 
gluten.  It  is  a  tenacious,  ductile,  elastic  substance. 
It  has  no  taste.  By  exposure  to  air  it  becomes  of 
a  brown  colour.  It  is  very  slightly  soluble  in  cold 
water  but  not  soluble  in  alcohol.  When  a  solution 
of  it  in  water  is  heated,  the  gluten  separates  in  the 
form  of  yellow  flakes  ;  in  this  respect  it  agrees  with 
albumen,  but  differs  from  it  in  being  infinitely  less 
soluble  in  water.  The  solution  of  albumen  does  not 
coagulate  when  it  contains  much  less  than  1000  parts 
of  albumen ;  but  it  appears  that  gluten  requires  more 
than  1000  parts  of  cold  water  for  its  solution* 


C         77         ] 

Gluten  when  burnt  affords  similar  products  to 
albumen,  and  probably  differs  very  little  from  it  in 
composition.  Gluten  is  found  in  a  great  number  of 
plants ;  Proust  discovered  it  in  acorns,  chesnuts, 
horse  chesnuts,  apples,  and  quinces  ;  barley,  rye,  peas 
and  beans  j  likewise  in  the  leaves  of  rue,  cabbage, 
cresses,  hemlock,  borage,  saffron,  in  the  berries  of 
the  elder,  and  in  the  grape.  Gluten  appears  to  be 
one  of  the  most  nutritive  of  the  vegetable  substances  ; 
and  wheat  seems  to  owe  its  superiority  to  other  grain, 
from  the  circumstance  of  its  containing  it  in  larger 
quantities. 

6.  Gum  elastic^  or  Caoutchouc^  is  procured  from 
the  juice  of  a  tree  which  grows  in  the  Brazils,  called 
Hsevea.  When  the  tree  is  punctured,  a  milky  juice 
exudes  from  it,  which  gradually  deposits  a  solid  sub- 
stance, and  this  is  gum  elastic. 

Gum  elastic  is  pliable  and  soft  like  leather,  and  be- 
comes softer  when  heated.  In  its  pure  state  it  is  white ; 
its  specific  gravity  is  9335.  It  is  combustible,  and 
burns  with  a  white  flame,  throwing  off  a  dense  smoke, 
with  a  very  disagreeable  smell.  It  is  insoluble  in  wa- 
ter, and  in  alcohol ;  it  is  soluble  in  ether,  volatile  oils, 
and  in  petroleum,  and  may  be  procured  from  ether  in 
an  unaltered  state,  by  evaporating  its  solution  in  that 
liquid.  Gum  elastic  seems  to  exist  in  a  great  variety 
of  plants :  amongst  them  are,  Jatropha  elastica,  Ficus 
indica^  Artocarpus  integrifoliay  and  Urceola  elastica. 

Bird-lime,  a  substance  which  may  be  procured 
from  the  holly,  is  very  analogous  to  gum  elastic  in  its 
properties.     Species  of  gum  elastic  may  be  obtained 


C  78  ] 

from  the  misletoe,  from  gummastic,  opium ^  and  from 
the  berries  of  the  Smilax  caduca^  in  which  last  plant  it 
has  been  lately  discovered  by  Dr.  Barton. 

Gum  elastic,  when  distilled,  affords  volatile  al- 
kali, water  hydrogene,  and  carbon  in  different  com- 
binations. It  therefore  consists  principally  of  azote, 
hydrogene,  oxygene,  and  carbon  ;  but  the  proportions 
in  which  they  are  combined  have  not  yet  been  ascer- 
tained. Gum  elastic  is  an  indigestible  substance,  not 
fitted  for  the  food  of  animals  ;  its  uses  in  the  arts  are 
well  known. 

7.  Extract^  or  the  extractive  principle^  exists  in 
almost  all  plants.  It  may  be  procured  in  a  state  of 
tolerable  purity  from  saffron,  by  merely  infusing  it  in 
water,  and  evaporating  the  solution.  It  may  likewise  be 
obtained  from  catechu,  or  Terra  japonica,  a  substance 
brought  from  India.  This  substance  consists  princi- 
pally of  astringent  matter,  and  extract ;  by  the  action 
of  water  upon  it,  the  astringent  matter  is  first  dissol- 
ved, and  may  be  separated  from  the  extract.  Extract 
is  always  more  or  less  coloured  ;  it  is  soluble  in  alcohol 
and  water,  but  not  soluble  in  ether.  It  unites  with  alu- 
mina when  that  earth  is  boiled  in  a  solution  of  ex- 
tract ,  and  it  is  precipitated  by  the  salts  of  alumina, 
and  by  many  metallic  solutions,  particularly  the  solu- 
tion of  muriate  of  tin. 

From  the  products  of  its  distillation,  it  seems  to 
be  composed  principally  of  hydrogene,  oxygene,  car- 
bon, and  a  little  azote. 

There  appears  to  be  almost  as  many  varieties  of 
extract  as  there  are  species  of  plants.    The  difference 


C  T9  ] 

of  their  properties  probably  in  many  cases  depends 
upon  their  being  combined  with  small  quantities  of 
other  vegetable  principles,  or  to  their  containing  differ- 
ent saline,  alkaline,  acid,  or  earthy  ingredients.  Many 
dyeing  substances  seem  to  be  of  the  nature  of  extrac- 
tive principle,  such  as  the  red  colouring  matter  of 
madder,  and  the  yellow  dye,  procured  from  weld. 

Extract  has  a  strong  attraction  for  the  fibres  of 
cotton  or  linen,  and  combines  with  these  substances 
when  they  are  boiled  in  a  solution  of  it.  The  com- 
bination is  made  stronger  by  the  intervention  of  mor- 
dants, which  are  earthy  or  metallic  combinations  that 
unite  to  the  cloth,  and  enable  the  colouring  matter  to 
adhere  more  strongly  to  its  fibres. 

Extract,  in  its  pure  form,  cannot  be  used  as  an 
article  of  food,  but  it  is  probably  nutritive  when  united 
to  starch,  mucilage,  or  sugar. 

8.  Tannin^  or  the  tanning  principle,  may  be  pro- 
cured by  the  action  of  a  small  quantity  of  cold  water 
on  bruised  grape- seeds,  or  pounded  gall-nut ;  and  by 
the  evaporation  of  the  solution  to  dryness.  It  appears 
as  a  yellow  substance,  possessed  of  a  highly  astrin- 
gent taste.  It  is  difficult  of  combustion.  It  is  very 
soluble  both  in  water  and  alcohol,  but  insoluble  in 
ether.  When  a  solution  of  glue,  or  isinglass  {gelatine) 
is  mixed  with  an  aqueous  solution  of  tannin,  the  two 
substances,  i.  e.  the  animal  and  vegetable  matters  fall 
down  in  combination,  and  form  an  insoluble  precipi- 
tate. 

When  tannin  is  distilled  in  close  vessels,  the  prin- 
cipal products  are  charcoal,  carbonic  acid,  and  inflam- 


C  80  ] 

mable  gasses,  with  a  minute  quantity  of  volatile  alkali. 
Hence  its  elements  seem  the  same  as  those  of  extract, 
but  probably  in  different  proportions.  The  charac- 
teristic property  of  tannin  is  its  action  upon  solutions 
of  isinglass  or  jelly  ;  this  particularly  distinguishes  it 
from  extract,  with  which  it  agrees  in  most  other  che- 
mical qualities. 

There  are  many  varieties  of  tannin,  which  pro- 
bably owe  the  difference  of  their  properties  to  com- 
binations with  other  principles,  especially  extract, 
from  which  it  is  not  easy  to  free  tannin.  The  purest 
species  of  tannin  is  that  obtained  from  the  seeds  of  the 
grape ;  this  forms  a  white  precipitate,  with  solution 
of  isinglass.  The  tannin  from  gall-nuts  resembles  it 
in  its  properties.  That  from  sumach  affords  a  yellow 
precipitate  ;  that  from  kino  a  rose  coloured ;  that 
from  catechu  a  fawn  coloured  one.  The  colouring 
matter  of  Brazil  wood,  which  M.  Chevreul  considers 
as  a  peculiar  principle,  and  which  he  has  called  Hema- 
iine^  differs  from  other  species  of  tannin,  in  affording 
a  precipitate  with  gelatine,  which  is  soluble  in  abun- 
dance of  hot  water.  Its  taste  is  much  sweeter  than 
that  of  the  other  varieties  of  tannin,  and  it  may  per- 
haps be  regarded  as  a  substance  intermediate  between 
tannin  and  extract. 

Tannin  is  not  a  nutritive  substance,  but  is  of 
great  importance  in  its  application  to  the  art  of  tanning. 
Skin  consists  almost  entirely  of  jelly  or  gelatine^  in  an 
organized  state,  and  is  soluble  by  the  long  continued 
action  of  boiling  water  When  skin  is  exposed  to  so- 
lutions containing  tannin,  it  slowly  combines  with 


c 


81 


3 


that  principle  ;  its  fibrous  texture  and  coherence  are 
preserved ;  it  is  rendered  perfectly  insoluble  in  water, 
and  is  no  longer  liable  to  putrefaction :  in  short,  it 
becomes  a  substance  in  chemical  composition  pre- 
cisely analogous  to  that  furnished  by  the  solution  of 
jelly  and  the  solution  of  tannin. 

In  general,  in  this  country,  the  bark  of  the  oak 
is  used  for  affording  tannin  in  the  manufacture  of 
leather ;  but  the  barks  of  some  other  trees,  particu- 
larly the  Spanish  chesnut,  have  lately  come  into  use. 
The  following  table  will  give  a  general  idea  of  the  re- 
lative value  of  different  species  of  barks.  It  is  founded 
on  the  result  of  experiments  made  by  mysi^lf. 

Table  of  Numbers  exhibiting  the  quantity  of  Tannin  af- 
forded by  480lbs.  of  different  Barks,  which  express 
nearly  their  relative  values. 


Average  of  entire  bark  of  middle  sized  Oak,  cut  in  spring, 

■"■""— — -—  of  Spanish  Chesnut, 

— — — , _  of  Leicester  Willow,  large  size, 

^— ————-*-. of     'm, 


large. 


—  of  Common  Willow, 
~  of  Ash,     - 

—  of  Beech, 

—  of  Horse  Chesnut, 

—  of  Sycamore, 

—  of  Lombardy  Poplar, 

—  of  Birch, 

—  ofH.zcl, 

—  of  Black  Thorn 

—  of  Coppice  Oak, 

—  of  Oak  cut  in  autumn, 
-~  of  Larch,  cut  in  autumn, 


White  interior  cortical  layers  of  Oak  Bark, 


lb. 
29 
21 
33 
13 
11 
16 
10 

9 
11 
15 

8 
14 
16 
33 
21 

8 
72 


The  quantity  of  the  tanning  principle  in  barks 
differs  in  different  seasons  j  when  the  spring  has  been 

M 


L        82        3 

cold  the  quantity  is  smallest.  On  an  average,  4  or 
5lbs.  of  good  oak  bark  are  required  to  form  lib.  of 
leather.  The  inner  cortical  layers  in  all  barks  con- 
tain the  largest  quantity  of  tannin.  Barks  contain  the 
greatest  proportion  of  tannin  at  the  time  the  buds  be- 
gin to  open — the  smallest  quantity  in  winter. 

The  extractive  or  colouring  matters  found  in 
barks,  or  in  substances  used  in  tanning,  influence  the 
quality  of  leather.  Thus  skin  tanned  with  gall-nuts 
is  much  paler  than  skin  tanned  with  oak  bark,  which 
contains  a  brown  extractive  matter.  Leatiier  made 
from  catechu  is  of  a  reddish  tint.  It  is  probable  that 
in  the  process  of  tanning,  the  matter  of  skin,  and  the 
tanning  principle  first  enter  into  union,  and  that  leather 
at  the  moment  of  its  formation  unites  to  the  extractive 
matter. 

In  general,  skins  in  being  converted  into  leather 
increase  in  weight  about  one  third  j*  and  the  opera- 
tion is  most  perfect  when  they  are  tanned  slowly. 
"When  skins  are  introduced  into  very  strong  infusions 
of  tannin,  the  exterior  parts  immediately  combine  with 
that  principle,  and  defend  the  interior  parts  from  the 
action  of  the  solution  :  such  leather  is  liable  to  crack 
and  to  decay  by  the  action  of  water. 

The  precipitates  obtained  from  infusions  contain- 
ing tannin  by  isinglass,  when  dried,  contain  at  a  medi- 
um rate  about  40  per  cent,  of  vegetable  matter.  It 
is  easy  to  obtain  the  comparative  value  of  different 
substances  for  the  use  of  the  tanner,  by  comparing 

*  This  estimation  must  be  considered  as  applying  to  dry  skin  and  dry  leather. 


C         83         3 

quantities  of  precipitate  afForded  by  infusions  of  given 
weights  mixed  with  solutions  of  glue  or  isinglass. 

To  make  experiments  of  this  kind,  an  ounce  or 
480  grains  of  the  vegetable  substance  in  coarse  pow- 
der, should  be  acted  upon  by  half  a  pint  of  boiling 
water.  The  mixture  should  be  frequently  stirred,  and 
suffered  to  stand  24  hours  ;  the  fluid  should  then  be 
passed  through  a  fine  linen  cloth  and  mixed  with  an 
equal  quantity  of  solution  of  gelatine,  made  by  dissolv- 
ing glue,  jelly,  or  isinglass  in  hot  water,  in  the  pro- 
portion of  a  drachm  of  glue  or  isinglass,  or  six  table 
spoonfuls  of  jelly,  to  a  pint  of  water.  The  precipitate 
should  be  collected  by  passing  the  mixture  of  the  solu- 
tion and  infusion  through  folds  of  blotting  paper ;  and 
tlie  paper  exposed  to  the  air  till  its  contents  are  quite 
dry.  If  pieces  of  paper  of  equal  weights  are  used,  in 
cases  in  which  different  vegetable  substances  are  em- 
ployed, the  difference  of  the  weights  of  the  papers 
when  dried,  will  indicate  with  tolerable  accuracy,  the 
quantities  of  tannin  contained  by  the  substances,  and 
their  relative  value,  for  the  purposes  of  manufacture. 
Four  tenths  of  the  increase  of  weight,  in  grains,  must 
be  taken,  which  will  be  in  relation  to  the  weights  in 
the  table. 

Besides  the  barks  already  mentioned,  there  are  a 
number  of  others  which  contain  the  tanning  principle. 
Few  barks  indeed  are  entire  free  from  it.  It  is  like- 
wise found  in  the  wood  and  leaves  of  a  number  of 
trees  and  shrubs,  and  is  one  of  the  most  generally  dif- 
fused of  the  vegetable  principles. 

A  substance  very  similar  to  tannin   has    been 


[  84  ] 

formed  by  Mr.  Hatchett,  by  the  action  of  heated  dilu- 
ted nitric  acid  on  charcoal,  and  evaporation  of  the 
mixture  to  dryness.  From  100  grains  of  charcoal 
Mr.  Hatchett  obtained  120  grains  of  artificial  tannin, 
which,  like  natural  tannin,  possessed  the  property  of 
rendering  skin  insoluble  in  water. 

Both  natural  and  artificial  tannin  form  com* 
pounds  with  the  alkalies  and  the  alkaline  earths ;  and 
these  compounds  are  not  decomposable  by  skin.  The 
attempts  that  have  been  made  to  render  oak  bark 
more  efficient  as  a  tanning  material  by  infusion  in  lime 
water,  are  consequently  founded  on  erroneons  princi- 
ples.    Lime  forms  with  tannin,  a  compound  not  so* 

luble  in  water. 

The  acids  unite  to  tannin,  and  produce  comi» 
pounds  that  are  more  or  less  soluble  in  water.  It  is 
probable  that  in  some  vegetable  substances  tannin 
exists,  combined  with  alkaline  or  earthy  matter ;  and 
such  substances  will  be  rendered  more  efficacious  for 
the  use  of  the  tanner,  by  the  action  of  diluted  acids. 

9.  Indigo  may  be  procured  from  woad  {Isatis  tinc- 
ioria,)  by  digesting  alcohol  on  it,  and  evaporating  the 
solution.  White  crystalline  grains  are  obtained, 
which  gradually  become  blue  by  the  action  of  the  at- 
mosphere :  these  grains  are  the  substance  in  question. 

The  indigo  of  commerce  is  principally  brought 
from  America.  Jt  is  procured  from  the  Indigofera 
argentea^  or  wild  indigo,  the  Indigofera  dispermUy  or 
Gautimala  indigo,  and  the  Indigofera  iinctoria,  or 
French  indigo.  It  is  prepared  by  fermenting  the 
leaves  of  those  trees  in  water.     Indigo  in  its  common 


C  85  ] 

form  appears  as  a  fine,  deep  blue  powder.  It  is  in- 
soluble in  water,  and  but  slightly  soluble  in  alcohol : 
its  true  solvent  is  sulphuric  acid  :  8  parts  of  sulphu- 
ric acid  dissolve  1  part  of  indigo  ;  and  the  solution 
diluted  with  water  forms  a  very  fine  blue  dye. 

Indigo,  by  its  distillation,  affords  carbonic  acid 
gas,  water,  charcoal,  ammonia,  and  some  oily  and 
acid  matter  :  the  charcoal  is  in  very  large  proportion. 
Pure  indigo  therefore  most  probably  consists  of  car- 
bon, hydrogene,  oxygene,  and  azote. 

Indigo  owes  its  blue  colour  to  combination  with 
oxygene.  For  the  uses  of  the  dyers  it  is  partly  de- 
prived of  oxygene,  by  digesting  it  with  orpiment  and 
lime  water,  when  it  becomes  soluble  in  the  lime  water, 
and  of  a  greenish  colour.  Cloths  steeped  in  this  so- 
lution combine  with  the  indigo  ;  they  are  green  when 
taken  out  of  the  liquor,  but  become  blue  by  absorb- 
Tng  oxgene  when  exposed  to  air. 

Indigo  is  one  of  the  most  valuable  and  most  ex- 
tensively used  of  the  dyeing  materials. 

10.  The  narcotic  principle  is  found  abundantly  in 
opium^  which  is  obtained  from  the  juice  of  the  white 
poppy,  {Fapaver  album).  To  procure  the  narcotic 
principle,  water  is  digested  upon  opium  :  the  solution 
obtained  is  evaporated  till  it  becomes  of  the  consistence 
of  a  syrup.  By  the  addition  .  of  cold  water  to  this 
syrup  a  precipitate  is  obtained.  Alchohol  is  boiled  on 
this  precipitate ;  during  ^the  cooling  of  the  alcohol 
crystals  fall  down.  These  crystals  are  to  be  again 
dissolved  in  alcohol,  and  again  precipitated  by  cool- 
ing :  and  the  process  is  to  be  repeated  till  their  colour 
is  white  ;  they  are  crystals  of  narcotic  principle. 


C         86        1 

The  narcotic  principle  has  no  taste  nor  smell.  It 
is  soluble  in  about  400  parts  of  boiling  water  ;  it  is 
insoluble  in  cold  water  :  it  is  soluble  in  24  parts  of 
boiling  alcohol,  and  in  100  parts  of  cold  alcohol.  It 
is  very  soluble  in  all  acid  menstrua. 

It  has  been  shewn  by  De  Rosne,  that  the  action 
of  opium  on  the  animal  economy  depends  on  this 
principle.  Many  other  substances  besides  the  juice 
of  the  poppy,  possess  narcotic  properties  ;  but  they 
have  not  yet  been  examined  with  much  attention. 
The  Lactuca  sativa^  or  garden  lettuce,  and  most  of 
the  other  lactucas  yield  a  milky  juice,  which  when 
inspissated  has  the  characters  of  opium,  and  probably 
contains  the  same  narcotic  principle. 

1 1 .  The  hitter  principle  is  very  extensively  diffus- 
ed in  the  vegetable  kingdom  ;  it  is  found  abundantly 
m  the  hop  {Humilus  lupilus^)  in  the  common  broom 
(Spartium  scoparium^  in  the  chamomile  (^Anihemis 
nobilis^)  and  in  quassia^  amara  and  exceha.  It  is  ob- 
tained from  those  substances  by  the  action  of  water  or 
alcohol,  and  evaporation.  It  is  usually  of  pale  yellow 
colour ;  its  taste  is  intensely  bitter.  It  is  very  solu- 
ble,  both  in  water  and  alcohol ;  and  has  little  or  no 
action  on  alkaline,  acid,  saline  or  metallic  solution. 

An  artificial  substance,  similar  to  the  bitter  prin- 
ciple,  has  been  obtained  by  digesting  diluted  nitric 
acid,  on  silk,  indigo,  and  the  wood  of  the  white  willow. 
This  substance  has  the  property  of  dyeing  cloth  of  a 
bright  yellow  colour  ;  it  differs  from  the  natural  bitter 
principle  in  its  power  of  combining  with  the  alkalies  : 
in  union  with  the  fixed  alkalies  it  constitutes  crystal- 


C         87         ] 

lized  bodies,  which  have  the  property  of  detonating 
by  heat  or  percussion. 

The  natural  bitter  principle  is  of  great  impor- 
tance in  the  art  of  brewing  ;  it  checks  fermentation, 
and  preserves  fermented  liquors  ;  it  is  likewise  used 
in  medicine. 

The  bitter  principle,  like  the  narcotic  principle, 
appears  to  consist  principally  of  carbon,  hydrogene, 
and  oxygene,  with  a  little  azote. 

12.  Wax  is  found  in  a  number  of  vegetables  ;  it 
is  procured  in  abundance  from  the  berries  of  the  wax 
myrtle  (Myrica  ceriferd)^  it  may  be  likewise  obtained 
from  the  leaves  of  many  trees  ;  in  its  pure  state  it  is 
white.  Its  specific  gravity  is  9,662  ;  it  melts  at  155 
degrees  ;  it  is  dissolved  by  boiling  alcohol ;  but  it  is 
not  acted  upon  by  cold  alcohol ;  it  is  insoluble  in  wa- 
ter ;  its  properties  as  a  combustible  body  are  well 
known. 

The  wax  of  the  vegetable  kingdom  seems  to  be  pre- 
cisely of  the  same  nature  as  that  afforded  by  the  bee. 
From  the  experiments  of  M.  M.  Gay  Lussac  and 
Thenard,  it  appears  that  100  parts  of  wax  consist  of 
Carbon         ...         -         81,784 
Oxygene       -        .         .        .  5,544" 

Hydrogene    .        «        .         .         12,672 
or  otherwise, 

Carbon  ....        81,784 

Oxygene  and  hydrogene  in  the  pro-") 

r  r  6,300 

portions  necessary  to  form  water  J 
Hydrogene  -        -        .         11,916 

which  agrees  very  nearly  with  37  proportions  of  hy- 
drogene, 21  of  charcoal,  1  ofoxygejie. 


I         88         3 

13.  Resin  is  very  common  In  the  vegetable  king- 
dom. One  of  the  most  usual  species  is  that  afforded 
by  the  different  kinds  of  fir.  When  a  portion  of  the 
bark  is  removed  from  a  fir  tree  in  spring,  a  matter 
exudes,  which  is  called  turpentine  ;  by  heating  this 
turpentine  gently,  a  volatile  oil  rises  from  it,  and  a 
more  fixed  substance  remains ;  this  substance  is 
resin. 

The  resin  of  the  fir  is  the  substance  commonly 
known  by  the  name  of  rosin  ;  its  properties  are  well 
known.  Its  specific  gravity  is  1 072.  It  melts  readily, 
burns  with  a  yellow  light,  throwing  off  much  smoke. 
Resin  is  insoluble  in  water  either  hot  or  cold  ;  but 
very  soluble  in  alcohol.  When  a  solution  of  resin  in 
alcohol  is  mixed  with  water,  the  solution  becomes 
milky ;  the  resin  is  deposited  by  the  stronger  attrac- 
tion of  the  water  for  the  alcohol. 

Resins  are  obtained  from  many  other  species  of 
trees.  Mastich^  from  the  Fistacia  lentiscus^  Elemi 
from  the  Amyris  elemifera^  Copal  from  the  Rhus  copal- 
linum^  Sandarach  from  the  common  juniper.  Of  these 
resins  copal  is  the  most  peculiar.  It  is  the  most  diffi- 
cultly dissolved  in  alcohol ;  and  for  this  purpose 
must  be  exposed  to  that  substance  In  vapour  ,  or  the 
alcohol  employed  must  hold  camphor  in  solution.  Ac- 
cording to  Gay  Lpssac  and  Thenard, 
100  parts  of  common  resin  contain 

Carbon  -         .         .         -         75,944 

Oxygene       .         -         -         .         13,337 
Hydrogene    -         -         -        -         10,719 


C         89' 

or  of 

Carbon  ....         75,944 

Oxygene  and  hydrogene  in  the  pro-  ^  ^  ^ 

1 1  oo 


1 15,: 


portions  necessary  to  form  water 
Hydrogene  in  excess       -         -  8,900 

According  to  the  same  chemists,  100  parts  of  co- 
pal consist  of 

Carbon  -        -        -         -         76,811 

Oxygene       -       --        -         -         10,606 
Hydrogene    ...         -         12,583 
or, 

Carbon         ....         76,811 
Water  or  its  elements     -        -         12,052 
Hyrogene      -         -      -  -        -         11,137 
From  these  results,  if  resin  be  a  definite  com- 
pound, it  may  be  supposed  to  consist  of  8  proportions 
of  carbon,  12  of  hydrogene,  and  1  of  oxygene. 

Resins  are  used  for  a  variety  of  purposes.  Tar 
and  pitch  principally  consist  of  resin,  in  a  partially  de- 
composed state.  Tar  is  made  by  the  slow  combustion 
of  the  fir  ;  and  pitch  by  the  evaporation  of  the  more 
volatile  parts  of  tar.  Resins  are  employed  as  var- 
nishes, and  for  these  purposes  are  dissolved  in  alco- 
hol or  oils.  Copal  forms  one  of  the  finest.  It  may 
be  made  by  boiling  it  in  powder  with  oil  of  rosemary, 
and  then  adding  alcohol  to  the  solution. 

14.  Camphor  is  procured  by  distilling  the  wood 
of  the  camphor  tree  (Laurus  Campbora,)  which  grows 
in  Japan.  It  is  a  very  volatile  body,  and  may  be  pu- 
rified by  distillation.  Camphor  is  a  white,  brittle, 
semitransparent  substance,  having  a  peculiar  odour, 

N 


C      90      3 

and  a  strong  acrid  taste.  It  is  very  slightly  soluble 
in  water  ;  more  than  1 00,000  parts  of  water  are  re- 
quired to  dissolve  1  part  of  camphor.  It  is  very  solu- 
ble in  alcohol ;  and  by  adding  water  in  small  quantities 
at  a  time  to  the  solution  of  camphor  in  alcohol,  the 
camphor  separates  in  a  crystallised  form.  It  is  solu- 
ble in  nitric  acid,  and  is  separated  from  it  by  water. 

Camphor  is  very  inflammable  ;  it  burns  with  a 
bright  flame,  and-  throws  oflf  a  great  quantity  of  car- 
bonaceous matter.  It  forms  in  combustion  water, 
carbonic  acid,  and  a  peculiar  acid  called  camphorici 
acid.  No  accurate  analysis  has  been  made  of  camphor, 
but  it  seems  to  approach  to  the  resins  in  its  composi- 
tion ;  and  consists  of  carbon,  hydrogene,  and  oxy- 
gene. 

Camphor  exists  in  other  plants  besides  the  Lau- 
rus  camphora.  It  is  procured  from  species  of  the  lau- 
rus  growing  in  Sumatra,  Borneo,  and  other  of  the 
East  Indian  isles.  It  has  been  obtained  from  thyme 
(Thymus  serpillum,')  marjorum  (Origanum  major  ana  ^^ 
Ginger  tree  (Amomurn  Zingiber.^  Sage  (Salvia  officin- 
alis,') Many  volatile  oils  yield  camphor  by  being 
merely  exposed  to  the  air. 

An  artificial  substance  very  similar  to  camphor 
has  been  formed  by  M.  Kind,  by  saturating  oil  of  tur- 
pentine with  muriatic  acid  gas  (the  gaseous  substance 
procured  from  common  salt  by  the  action  of  sulphuric 
acid).  The  camphor  procured  in  well  conducted  ex- 
periments amounts  to  half  of  the  oil  of  turpentine 
used.  It  agrees  with  common  camphor  in  most  of  its 
sensible  properties  j  but  diflfers  materially  in  its  che- 


[    ■      91  ] 

mical  qualities  and  composition.  It  is  not  soluble 
without  decomposition  in  nitric  acid.  From  the  ex- 
periments of  Gehlen,  it  appears  to  consist  of  the  ele- 
ments of  oil  of  turpentine,  carbon,  hydrogene  and 
oxygene,  united    to  the   elements   of  muriatic  gas, 

chlorine  and  hydrogene. 

From  the  analogy  of  artificial  to  natural  camphor, 

-it  does  not  appear  improbable,  that  natural  camphor 
may  be  a  secondary  vegetable  compound,  consisting 
of  camphoric  aciil  and  volatile  oil.  Camphor  is  used 
medicinally,  but  it  has  no  other  application. 

15.  Fixed  oil  is  obtained  by  expression  from  seeds 
and  fruits  ;  the  olive,  the  almond,  linseed  and  rape- 
seed  afford  the  most  common  vegetable  fixed  oils. 
The  properties  of  fixed  oils  are  v^ell  known.  Their 
specific  gravity  is  less  than  that  of  water  ;  that  of  olive 
and  of  rape-seed  oil  is  913;  that  of  linseed  and  al- 
mond oil  932  ;  that  of  palm  oil  968  ;  that  of  walnut 
and  beech  mast  oil  923.  Many  of  the  fixed  oils  con- 
geal at  a  lower  temperature  than  that  at  which  water 
freezes.  They  all  require  for  their  evaporation  a 
higher  temperature  than  that  at  which  water  boils. 
The  products  of  the  combustion  of  oil  are  water,  and 
carbonic  acid  gas. 

From  the  experiments  of  Gay  Lussac  and  Then- 
ard,  it  appears  that  olive  oil  contains,  in  lOO  parts. 
Carbon         -        -         .      .  -        77,213 
Oxygene       -        -        -        -  9,427 

Hydrogene    -         .         .         -         13,360 
This  estimation  is  a  near  approximation  to  1 1  pro* 
portions  of  carbon,  20  hydrogene,  and  1  oxygene. 


C         92         J 

The  following  is  a  list  of  fixed  oils,  and  of  the 
trees  that  afford  them. 

Olive  oil,  from  the  Olive  tree  (Oka  Europea)^ 
Linseed  oil,  from  the  copimon  and  perennial  Flax 
{Linum  usitatissimum  et  perenne^  Nut  oil,  from  the 
Hazel  nut  {Coryllus  avelland)^  Walnut  (/wg-A^wj  regid)^ 
Hemp  oil,  from  the  Hemp  {Cannabis  sativa\  Almond 
oil,  from  the  sweet  Almond  {Amygdalus  communis)^ 
Beech  oil,  from  the  common  Beech  (Fagus  sylvatica)^ 
Rape-seed  oil,  from  the  Rapes  {Brassica  napus  et  cam- 
pestris\  Poppy  oil,  from  the  Poppy  {Fapaver  somnife- 
rum)^  oil  of  Sesamum,  from  the  Sesamum  (Sesamum 
orientak)^  Cucumber  oil,  from  the  Gourds  {Cucurbita 
pepo  et  malapepo)^  oil  of  Mustard,  (Sinapis  nigra  et  ar- 
vensis)^  oil  of  Sunflower,  from  the  annual  and  peren- 
nial Sunflower,  (Heliantbus  annuus  et  perennis).  Castor 
oil,  from  the  Palma  Christi  (Ricinus  communis)^  To- 
bacco (Nicotiana  tabacum  et  rustica\  Plum  kernel  oil, 
from  the  Plum  tree  (Prunus  domestica').  Grape-seed 
oil,  from  the  Vine  (Vitis  vinifera\  Butter  of  cacoa, 
from  the  Cacoa  tree  (Theobroma  cacoa^  Laurel  oil, 
from  the  sweet  Bay  tree  {Laurm  nobilii). 

The  fixed  oils  are  very  nutritive  substances ;  they 
are  of  great  importance  in  their  applications  to  the 
purposes  of  life.  Fixed  oil,  in  combination  with  soda, 
forms  the  finest  kind  of  hard  soap.  The  fixed  oils 
are  used  extensively  in  the  mechanical  arts,  and  for 
the  preparation  of  pigments  and  varnishes. 

16.  Volatile  oil,  likewise  called  essential  oil,  differs 
from  fixed  oil,  in  being  capable  of  evaporation  by  a 
much  lower  degree  of  heat  j  in  being  soluble  in  alco- 


[         93         ] 

hol,  and  in  possesslrg  a  very  slight  degree  of  solubili- 
ty in  water. 

There  is  a  great  number  of  volatile  oils,  distin- 
guished by  their  smell,  their  taste,  their  specific  gra- 
vity, and  other  sensible  qualities.  A  strong  and  pecu- 
liar odour  may  however  be  considered  as  the  great 
characteristic  of  each  species  ;  the  volatile  oils  inflame 
with  more  facility  than  the  fixed  oils,  and  afford  by 
their  combustion  different  proportions  of  the  same 
substances,  water,  carbonic  acid,  and  carbon. 

The  following  specific  gravities  of  different  vola-. 
tile  oils  were  ascertained  by  Dr.  Lewis. 

Oil  of  Sassafras       1094       Oil  of  Tansy       946 


Cinnamon 

1035 

' Caraway    940 

Cloves 

1034 

Origanum  940 

Fennel 

997       " 

Spike          936 

Dill 

994       . 

Rosemary  934 

Penny  Royal 

:  978 

Juniper      9 1 1 

Cummin 

975       - 

- —  Oranges     888 

Mint 

975      - 

—  Turpentine  792 

Nutmegs         948 

The  peculiar  odours  of  plants  seem,  in  almost 
all  cases,  to  depend  upon  the  peculiar  volatile  oils  they 
contain.  All  the  perfumed  distilled  waters  owe  their 
peculiar  properties  to  the  volatile  oils  they  hold  in  so- 
lution. By  collecting  the  aromatic  oils,  the  fragrance 
of  flowers,  so  fugitive  in  the  common  course  of  na- 
ture, is  as  it  were  embodied  and  made  permanent. 

It  cannot  be  doubted  that  the  volatile  oils  con- 
sist of  carbon,  hydrogene,  and  oxygene  ;  but  no  ac- 
curate experiments  have  as  yet  been  made  on  the 
proportions  in  which  these  elements  are  combined. 


C         94         ] 

The  volatile  oils  have  never  been  used  as  articles 
of  food  5  many  of  them  are  employed  in  the  arts,  in 
the  manufacture  of  pigments  and  varnish  ;  but  their 
most  extensive  application  is  as  perfumes. 

17  Woody  fibre  is  procured  from  the  wood,  bark, 
leaves,  or  flowers  of  trees,  by  exposing  them  to  the 
repeated  action  of  boiling  water  and  boiling  alcohol. 
It  is  the  insoluble  matter  that  remains,  and  is  the  basis 
of  the  solid  organised  parts  of  plants.  There  are  as 
many  varieties  of  woody  fibre  as  there  are  plants  and 
organs  of  plants ;  but  they  are  all  distinguished  by 
their  fibrous  texture,  and  their  insolubility. 

Woody  fibre  burns  with  a  yellow  flame,  and  pro- 
duces water  and  carbonic  acid  in  burning  When  it 
is  distilled  in  close  vessels,  it  yields  a  considerable 
residuum  of  charcoal.  It  is  from  woody  fibre,  indeed, 
that  charcoal  is  procured  for  the  purposes  of  life. 

The  following  table  contains  the  results  of  expe- 
riments made  by  Mr.  Mushet,  on  the  quantity  of  char- 
coal afibrded  by  different  wood. 


Lignum  Vitas 

26,8  of  charcoal 

Mahogany 

25,4 

Laburnum 

24,5 

Chesnut    - 

23,2 

Oak 

22,6 

American  black  Beech  2 1 ,4 

Walnut      - 

20,6 

Holly 

19,9 

Beech 

19,9 

American  Maple 

19,9 

Elm           .        - 

19,5 

C         95  3 

100  parts  of  Norway  Pine  -         19,2  of  charcoal 

Sallow       -  -         18,4 

Ash  -  -         17,9 


-Birch         -         -         17,4 
-  Scottish  Fir         -         1 6,4 


M.  Gay  Lussac  and  Thenard  have  concluded 
from  their  experiments  on  the  wood  of  the  oak  and 
the  beech,  that  100  parts  of  the  first  contain  : 

of  Carbon      -         -         .         .  52,53 

—  Oxygene  -         -         .  41,78 

—  Hydrogene        -         -         .  5,69 
and  100  parts  of  the  second  : 

of  Carbon      -         -         -         -  51,45 

—  Oxygene  ...  42,73 

—  Hydrogene        -         -         .  5,82 
Supposing  woody  fibre  to  be  a  definite  compound, 

these  estimations  lead  to  the  conclusion,  that  it  con- 
sists of  5  proportions  of  carbon,  3  of  oxygene,  and 
6  of  hydrogene ;  or  57  carbon,  45  oxygene,  and  6 
hydrogene. 

It  will  be  unnecessary  to  speak  of  the  applications 
of  woody  fibre.  The  different  uses  of  the  woods, 
cotton,  linen,  the  barks  of  trees,  are  sufficiently 
known.  Woody  fibre  appears  to  be  an  indigestible 
substance. 

1 8.  The  acids  found  in  the  vegetable  kingdom 
are  numerous  ;  the  true  vegetable  acids  which  exist 
ready  formed  in  the  juices  or  organs  of  plants,  are 
the  oxalic^  citric,  tartaric,  benzoic,  acetic,  malic,  gallic, 
and  prussic  acid. 


C         96         3 

All  these  acids,  except  the  acetic,  malic,  and 
prussic  acids,  are  white  crystallized  bodies.  The 
acetic,  malic,  and  prussic  acids  have  been  obtained  in 
the  only  fluid  state  ;  they  are  all  more  or  less  solu- 
ble in  water ;  all  have  a  sour  taste  except  the  gallic 
and  prussic  acids  ;  of  which  the  first  has  an  astringent 
taste,  and  the  latter  a  taste  like  that  of  bitter  almonds. 

The  oxalic  acid  exists,  uncombined,  in  the  liquor 
which  exudes  from  the  Chich  pea  (Cicer  arietinuni), 
and  may  be  procured  from  wood  sorrel  (Oxalis  aceto- 
5ella\  common  sorrel,  and  other  species  of  Rumex ; 
and  from  the  Geranium  acidum.  Oxalic  acid  is  easily 
discoved  and  distinguished  from  other  acids  by  its 
property  of  decomposing  all  calcareous  salts,  and 
forming  with  lime  a  salt  insoluble  in  water  ;  and  by 
its  crystallizing  in  four-sided  prisms. 

The  citric  acid  is  the  peculiar  acid  existing  in  the 
juice  of  lemons  and  oranges.  It  may  likewise  be  ob- 
tained from  the  cranberry,  whortleberry,  and  hip. 

Citric  acid  is  distinguished  by  its  forming  a  salt 
insoluble  in  water  with  lime ;  but  decomposable  by 
the  mineral  acids. 

The  tartaric  acid  may  be  obtained  from  the  juice 
of  mulberries  and  grapes  ;  and  hkewise  from  the  pulp 
of  the  tamarind.  It  is  characterized  by  its  property 
of  forming  a  difficultly  soluble  salt  with  potassa,  and 
an  insoluble  salt  decomposable  by  the  mineral  acids 
with  lime. 

Benzoic  acid  may  be  procured  from  several  re- 
sinous substances  by  distillation ;  from  benzoin, 
storax,  and  balsam  of  Tolu.    It  is  distinguished  from 


C         97         ] 

the  other  acids  by  its  aromatic  odour,  and  by  its  ex- 
treme volatility. 

Malic  acid  may  be  obtained  from  the  juice  of 
apples,  barberries,  plums,  elderberries,  currants, 
stawberries,  and  raspberries.  It  forms  a  soluble  salt 
with  lime ;  and  is  easily  distinguished  by  this  test 
from  the  acids  already  named. 

Acetic  acid,  or  vinegar,  may  be  obtained  from 
the  sap  of  different  trees.  It  is  distinguished  from 
malic  acid  by  its  peculiar  odour  ;  and  from  the  other 
vegetable  acids  by  forming  soluble  salts  with  the  alka- 
lies and  earths. 

Gallic  acid  may  be  obtained  by  gently  and  gradu- 
ally heating  powdered  gall  nuts,  and  receiving  the  vo- 
latile matter  in  a  cool  vessel.  A  number  of  white 
crystals  will  appear,  which  are  distinguished  by  their 
property  of  rendering  solutions  of  iron,  deep  purple. 

The  vegetable  prussic  acid  is  procured  by  distil- 
ling laurel  leaves,  or  the  kernels,  of  the  peach,  and 
cherry,  or  bitter  almonds.  It  is  characterized  by  its 
property  of  forming  a  blueish  green  precipitate,  when 
a  little  alkali  is  added  to  it,  and  it  is  poured  into  solu- 
tions containing  iron.  It  is  very  analogous  in  its  pro- 
perties to  the  prussic  acid  obtained  from  animal  sub- 
stances ;  or  by  passing  ammonia  over  heated  charcoal ; 
but  this  last  body  forms,  with  the  red  oxide  of  iron, 
the  deep  bright  blue  substance,  called  Prussian  blue. 

Two  other  vegetable  acids  have  been  found  in 
the  products  of  plants  ;  the  morolyxic  acid  in  a  saline 
exudation  from  the  white  mulberry  tree,  and  the  kinic 
acid  in  a  salt  afforded  by  Peruvian  bark  ;  but  these 


c     98     : 

two  bodies  have  as  yet  been  discovered  in  no  othei* 
cases.  The  phosphoric  acid  is  found  free  in  the 
onion ;  and  the  phosphoric,  sulphuric,  muriatic,  and 
nitric  acids,  exist  in  many  saline  compounds  in  the 
vegetable  kingdom ;  but  they  cannot  with  propriety 
be  considered  as  vegetable  products.  Other  acids 
are  produced  during  the  combustion  of  vegetable 
compounds,  or  by  the  action  of  nitric  acid  upon 
them ;  they  are  the  camphoric  acid,  the  mucous  or 
saclactic  acid,  and  the  suberic  acid ;  the  first  of  which 
is  procured  from  camphor  ;  the  second  from  gum  or 
mucilage  ;  and  the  third  from  cork,  by  the  action  of 
nitric  acid. 

From  the  experiments  that  have  been  made  upon 
the  vegetable  acids,  it  appears  that  all  of  them,  except 
the  prussic  acid,  are  constituted  by  different  propor- 
tions of  carbon,  hydrogene,  and  oxygene  ;  the  prus- 
sic acid  consists  of  carbon,  azote  and  hydrogene,  with 
a  little  oxygene.  The  gallic  acid  contains  more  car- 
bon than  any  of  the  other  vegetable  acids. 

The  following  estimates  of  the  composition  of 
some  of  the  vegetable  acids  have  been  made  by  Gay 
Lussac  and  Thenard. 
100  parts  of  oxalic  acid  contain  : 

Carbon  .         -         -         -         26,566 

Hydrogene    -         -         -         -  2,745 

Oxygene        -.         -         -         ,         70,689 
Ditto  of  tartaric  acid  : 

Carbon  -         -         .         -         24,050 

Hydrogene    -         .         -         -  6,629 

Oxygene       -         -         .         .,         69^321 


i:     99     ] 

100  parts  of  citric  acid  : 

Carbon  .         -         .         -         33,811 

Hydrogene    -         -         -         -  6,330 

Oxygene       -         .         .         -         59,859 
Ditto  acetic  acid : 

Carbon  -         -         -         .         50,224 

Hydrogene  -         .         .  5,620 

Oxygene        -         -         -         -         44,147 
Ditto  mucous  or  saclactic  acid  ; 

Carbon  .         -         .         .  33,69 

Hydrogene  -         -         -  3,62 

Oxygene       -         -         -         .  62,69 

These  estimations  agree  nearly  with  the  follow- 
ing definite  proportions.  In  oxalic  acid  7  proportions 
of  carbon,  8  of  hydrogene,  and  15  oxygene;*  in  tar- 
taric acid,  8  carbon,  28 hydrogene,  18  oxygene;  in 
citric  acid,  3  carbon,  6  hydrogene,  4  oxygene ;  in 
acetic  acid,  18  carbon,  22  hydrogene,  12  oxygene; 
in  mucous  acid,  6  carbon,  7  hydrogene,  8  oygene. 

The  applications  of  the  vegetable  acids  are  well 
known.  The  acetic  and  citric  acids  are  extensively 
used.  The  agreeable  taste  and  wholesomeness  of 
various  vegetable  substances  used  as  food,  materially 
depend  upon  the  vegetable  acid  they  contain. 

19.  Fixed  Alkali  may  be  obtained  in  aqueous  so- 
lution from  most  plants  by  burning  them,  and  treat- 
ing the  ashes  with  quick  lime  and  water.     The  vege- 


*  According  to  Dr.  Thompson's  experiments,  oxalic  acid  consists  of  3  pro- 
portions of  carbon,  4  of  oxygene,  and  4  of  hydrogene,  a  result  very  different  indeed 
from  that  of  the  French  chemists. 


C      100      j 

table  alkali,  or  potassa,  Is  the  common  alkali,  or  pot- 
assa,  is  the  common  alkali  in  the  vegetable  kingdom. 
This  substance  in  its  pure  state  is  white,  and  semi- 
transparent,  requiring  a  strong  heat  for  its  fusion,  and 
possessed  of  a  highly  caustic  taste.  In  the  matter 
usually  called  pure  potassa  by  chemists,  it  exists  com- 
bined with  water  ;  and  in  that  commonly  called  pearl 
ashes,  or  pot-ashes  in  commerce,  it  is  combined  with 
a  small  quantity  of  carbonic  acid.  Potassa  in  its  com- 
bined state,  as  has  been  mentioned,  page  47,  consists 
of  the  highly  inflammable  metal  potassium,  and  oxy- 
gene,  one  proportion  of  each. 

Soda,  or  the  mineral  alkali,  is  found  in  some 
plants  that  grow  near  the  sea ;  and  is  obtained  com- 
bined with  water,  or  carbonic  acid,  in  the  same  man- 
ner as  potassa ;  and  consists,  as  has  been  stated, 
page  47,  of  one  proportion  of  sodium,  and  two  pro- 
portions of  oxygene.  In  its  properties  it  is  very  simi- 
lar to  potassa  ;  but  may  be  easily  distinguished  from  it 
by  this  character :  it  forms  a  hard  soap  with  oil ; 
potassa  forms  a  soft  soap. 

Pearl  ashes,  and  barilla  and  kelp,  or  the  impure 
soda  obtained  from  the  ashes  of  marine  plants,  are 
very  valuable  in  commerce,  principally  on  account  of 
their  uses  in  the  manufacture  of  glass  and  soap.  Glass 
is  made  from  fixed  alkali,  flint,  and  certain  metallic 
substances. 

To  know  whether  a  vegetable  yields  alkali,  it 
should  be  burnt,  and  the  ashes  washed  with  a  small 
quantity  of  water.  If  the  water,  after  being  for  some 
time  exposed  to  the  air,  reddens  paper  tinged  with 


C      101       3 

turmeric  ;  or  renders  vegetable  blues,  green,  it  con- 
tains alkali. 

To  ascertain  the  relative  quantities  of  pot-ashes 
afforded  by  different  plants,  equal  weights  of  them 
should  be  burnt :  the  ashes  washed  in  twice  their 
volume  of  water ;  the  washings  should  be  passed 
through  blotting  paper,  and  evaporated  to  dryness : 
the  relative  weights  of  the  salt  obtained,  will  indicate 
very  nearly  the  relative  quantities  of  alkali  they  con- 
tain. 

The  value  of  marine  plants  in  producing  soda, 
may  be  estimated  in  the  same  manner,  with  sufficient 
correctness  for  all  commercial  purposes. 

Herbs,  in  general,  furnish  four  or  five  times,  and 
shrubs  two  or  three  times  as  much  pot-ashes  as  trees. 
The  leaves  produce  more  than  the  branches,  and  the 
branches  more  than  the  trunk.  Vegetables  burnt  in 
a  green  state  produce  more  ashes  than  in  a  dry  state. 

The  following  table*  contains  a  statement  of  the 
quantity  of  pot-ashes  afforded  by  some  common  trees 
and  plants. 

10,000  parts  of  Oak      -         -         15 

of  Elm      -        .        39 

of  Beech  -         -         12 

...«««._-,«-.  of  Vine     -         -         55 

of  Poplar  -        -  7 

of  Thistle  -        53 

of  Fern     -         -         62 

of  Cow  Thistle  -       196 

•  It  is  foandcd  upon  the  experiments  of  Kirwan,  Vaoqaelin  and  Pertuis. 


[         102         3 

10,000  parts  of  Wormwood   -  730 

_ of  Vetches  -  275 

of  Beans    -         -  200 

of  Fumitory       -  790 

The  earths  found  in  plants  are  four  :  silica  or 
the  earth  of  flints,  alumina  or  pure  clay,  lime  and 
magnesia.  They  are  procured  by  incineration.  The 
lime  is  usually  combined  with  carbonic  acid.  This 
substance  and  silica  are  much  more  common  in  the 
vegetable  kingdom  than  magnesia,  and  magnesia  more 
common  than  alumina.  The  earths  form  a  principal 
part  of  the  matter  insoluble  in  water,  afforded  by  the 
ashes  of  plants.  The  silica  is  known  by  not  being 
dissolved  by  acids  ;  the  calcareous  earth,  unless  the 
ashes  have  been  very  intensely  ignited,  dissolves  with 
effervescence  in  muriatic  acid.  Magnesia  forms  a  solu- 
ble and  crystallizable  salt,  and  lime,  a  difficultly  solu- 
ble one  with  sulphuric  acid.  Alumina  is  distinguished 
from  the  other  earths,  by  being  acted  upon  very  slowly 
by  acids  ;  and  in  forming  salts  very  soluble  in  water, 
and  difficult  of  crystallization  with  them. 

The  earths  appear  to  be-compounds  of  the  pecu- 
liar metals  mentioned  page  48  and  oxygene,  one  pro- 
portion of  each. 

The  earths  afforded  by  plants  are  applied  to  no 
uses  of  common  life  ;  and  there  are  few  cases  in 
which  the  knowledge  of  their  nature  can  be  of  impor- 
tance, or  afford  interest  to  the  farnief. 

The  only  metallic  oxides  found  in  plants,  are  those 
of  iron  and  manganesum :  they  are  detected  in  the 


C  103  -} 

ashes  of  plants  ;  but  In  very  minute  quantities  only. 
When  the  ashes  of  plants  are  reddish  brown,  they 
abound  in  oxides  of  iron.  When  black  or  purple,  in 
oxide  of  manganesum  ;  when  these  colours  are  mixed 
they  contain  both  substances. 

The  saline  compounds  contained  in  plants,  or 
afforded  by  their  incineration,  are  very  various.  The 
sulphuric  acid  combined  with  potassa,  or  sulphate  of 
potassa,  is  one  of  the  most  usual.  Common  salt  is 
likewise  very  often  found  in  the  ashes  of  plants  ;  like- 
wise phosphate  of  lime,  which  is  insoluble  in  water, 
but  soluble  in  muriatic  acid.  Compounds  of  the  nitric, 
muriatic,  sulphuric,  and  phosphoric  acids,  with  alkalies 
and  earths,  exist  in  the  sap  of  many  plants,  or  are  af- 
forded by  their  evaporation  and  incineration.  The 
salts  of  potassa  are  distinguished  from  those  of  soda, 
by  their  producing  a  precipitate  in  solutions  of  pla- 
tina  :  those  of  lime  are  characterized  by  the  cloudiness 
they  occasion  in  solutions  containing  oxalic  acid ; 
those  of  magnesia,  by  being  rendered  cloudy  by  solu- 
tions of  ammonia.  Sulphuric  acid  is  detected  in  salts 
by  the  dense  white  precipitate  it  forms  in  solutions  of 
baryta.  Muriatic  acid  by  the  cloudiness  it  communi- 
cates to  solution  of  nitrat  of  silver ;  and  when  salts 
contain  nitric  acid,  they  produce  scintillations  by  being 
thrown  upon  burning  coals. 

As  no  applications  have  been  made  of  any  of  the 
neutral  salts,  or  analogous  compounds  found  in  plants, 
in  a  separate  state,  it  will  be  useless  to  describe  them 
individually.     The  following  tables  are  given  from 


[ 


104 


3 


M.  Th.  de  Saussure's  Researches  on  Vegetation,  and 
contain  results  obtained  by  that  philosopher.  They 
exhibit  the  quantities  of  soluble  salts,  metallic  oxides, 
and  earths  afforded  by  the  ashes  of  different  plants. 


* 

Constituents  of  100  parts      i 

of  the  Ashes.                    | 

en 

U4 

o 

i 

i 

O 

Ui 

e 

f  £ 

'Si 

O 

5 

Si 

2 

CO 

s 

1 

1 

o 
1 

2 

i 

^ 

(U    *• 

J3 

^ 

I 

< 

1 

T45 

47 

24 

0,12 

Leaves  of  oak  (guercus  robur)  May  10 

13 

53 

3 

0,64  25,841 

2 

Ditto,  Sept.  27            ... 

24 

55 

549 

17 

18,25 

23 

14,5 

1,75  25,5  I 

3 

Wood  of  a  young  oak.  May  lO 

— 

4 



26 

28,5 

12,25 

0,12 

1        32,58. 

4 

Bark  of  ditto 

— 

60 



7 

4,5 

63.25 

0,25 

1,7522,75! 

5 

Entire  wood  of  oak 

— 

2 



38,6 

4,5 

32 

2 

2,25  20,65 

6 

Alburnum  of  ditto    - 

— 

— 



32 

24 

11 

7,5 

2       23,5 

7 

Bark  of  ditto    .... 

— 

60 



7 

3 

66 

1,5 

2      '21,5 

8 

Cortical  layers  of  ditto 

— 

73 

. 

7 

3,75 

65 

0,5 

1 

22,7i 

9 

Extract  of  wood  of  ditto  - 

— 

61 



51 

10 

Soil  from  wood  of  ditto     . 

— 

41 



24 

10,5 

10 

32 

14 

8,5 

11 

Extract  from  ditto  ... 

— 

111 



66 

12 

Leaves  of  the  poplar  (poputus  nigra) 

— 

May  26           .... 

23 

66 

652 

36 

13 

29 

5 

1,2515,75 

13 

Ditto  Sept.  12            ... 

41 

93 

565 

ai 

7 

36 

11,5 

1,5    18 

14 

Wood  of  ditto,  Sept.  12 

— 

8 

26 

— 

16,75 

27 

3,3 

1,5    24,5 

15 

Bark  of  ditto    .... 

— 

72 

6 

5,3 

60 

4 

1,5    23,2 

16 

Leaves  of  hazel    (corylus  avellana) 

May  1           .... 

— 

6l 



26 

23,3 

22 

2,5 

1,5  24,7 

17 

Ditto,  washed  in  cold  water 

— 

S7 



8,2 

19,5 

44.1 

4 

2      j22,2 

is 

Leaves  of  ditto  June  22     - 

28     1 

62 

655 

22,7 

14 

29 

11,3 

1,5 

21,5 

19 

Ditto  Sept.  20  - 

31 

70 

557 

11 

12 

36 

22 

2 

17 

20 

Wood  of  ditto.  May  1 

— 

5 



24,5 

35 

8 

0.25 

0,12 

32,2 

21 

Bark  of  ditto  .... 

— 

62 



12,5 

S,S 

54 

0,25 

1,75 

26 

22 

Entire  wood  of  mulberry  {morui  ni- 

gra), November     ... 

— 

7 



21 

2,25 

56 

0,12 

0,25  20,38 

23 

Alburnum  of  ditto     - 

— 

13 

. 

26 

27,25 

24 

1 

0,25:21,5 

24 

Bark  of  ditto             ... 

— 

89 



7 

8,5 

45 

15,25 

1,12  23,13 

25 

Cortical  layers  of  ditto     . 

— 

8S 



10 

16,5 

48 

0,12 

1 

24,38 

26 

Entire  wood  of  hornbeam  {carpinui 

betulHi),  Nov. 

4 

6 

346 

22 

23 

26 

0,12 

2,25 

26,63 

27 

Alburnum  of  ditto    ... 

4 

7 

390 

18 

36 

15 

1 

1 

29 

28 

Bark  of  ditto               ... 

88 

134 

346 

4,5 

4,5 

59 

1,5 

0,12  30,38| 

29>Wood  of  horse  chesnut  (asculus  hyp. 

1     pocastanum)  May  10      -        - 

~ 

35 



9,5 

30  Leaves  of  ditto.  May  10     - 

16 

72 

782 

50 

31  Leaves  of  ditto,  July  23    - 

29 

84 

652, 

24 

32  Ditto,  Sept.  27 

31 

86 

630 

13,5 

33'Flowers  of  ditto.  May  10 

9 

71 

873 

50 

'          \ 

105 


o 

CO 

o 

B 

a 
1^ 


34  Fruit  of  horse  chesnut  (asculus  hyp- 
fiocastanum)  Oct.  5        -         - 

Plants  of  peas  {pi sum  iativum)\n  flo*r 

Ditto,  ripe        .... 

Plants  of  vetches  (vicia  faba),  be- 
fore flowering.  May  23 

Ditto  in  flower,  June  23    - 

Ditto  ripe,  June  23   - 

Ditto,  seeds  separated 

Seeds  of  ditto 

Do.  in  flower,  rais'd  in  distilled  water 

Solydago  vulgaris,  before  flowering, 
May  1  -         .         -  *     - 

Ditto,  just  in  flower,  July  15     - 

Ditto,  seeds  ripe,  Sep.  20 

Plants  of  turnsol  (helianthus  annuus), 
a  month  before  flowering,  June  23 

Ditto  in  flower,  July  23    - 

Ditto,  bearing  ripe  seeds,  Sept.  20 

Wheat  (triticum  sativum),  in  flower 

Ditto,  seeds  ripe       .         -         - 

Ditto,  a  month  before  flowering 

Ditto,  in  flower,  June  14    - 

Ditto,  seeds  ripe       ... 

Straw  of  wheat 

Seeds  of  ditto  .         .         - 

Bran         -         -         -         -         > 

Plants  of  maize  (zea  mays)  a  month 
before  flowering,  June  23 

Ditto,  in  flower,  July  23 

Ditto,  seeds  ripe       ... 

Stalks  of  ditto 

Spikes  of  ditto 

Seeds  of  ditto  .         ,         - 

ChafF  of  barley  (hordeum  vulgare) 

Seeds  of  ditto 

Ditto 

Oats 

Leaves  of  rhododendron  ferrugineum, 
raised  on  Jura,  a  limestone  moun- 
tain, June  20  •         - 

Ditto,  raised  on  Breven,  a  granitic 
mountain,  June  27 

Branches  of  ditto,  June,  20 

Spikes  of  ditto,  June  27    - 

Leaves  of  fir  {pinus  abies),  raised  on 
Jura,  June  20         -         -         - 

Ditto,  raised  on  Breven,  June  27 

Branches  ©f  pine, June  20 

Whortleberry  (yaccinium  myrtillus), 
raised  on  Jura,  Aug.  29 
75  Ditto,  raised  on  Breven     - 


!l50 
[\22 
66 
115 
33 
39 
I 
92 
57 
50 

147 
137 
93 


O    M 
o   ^ 


_ 

29 

— 

29 

— 

15 

_ 

26 

— 

22 

Constituents  of  lOO  parts 
of  the  Ashes. 


647    82       l: 

i49,80'l7,25 

;34>25j22 

ii  I 

895lj55,5 

876  1155,5 

—.150 


42 


(14,5 
1 13,5 
117,75 
5,75 


69,28127,92 
60,1    30 


699 


67,5 

59 

43 

63 
61 

5,15 
43,35 
11 
60 
41 
10 
22,5 
47,16 

4,16 

69 
69 

72/45 

62 
20 
29 
22 
1 


23 

21,1 

22,5 
24 

16 
15 
15 

17 
24 


l0,75 

59 

II 

67 

6 
22,5 
12,75 
15 
11,5 
10,75 
11,75 

6,2 
44,5 
46,5, 

5,75 
6 


36 
7,75 
32,5 
22 
24 


6 
14 

3,5 
4,12 
4 

3§ 


1,5 
1,5 

17,25 

11,56 

12,5 

4 

0,25 
0,25 
0,25 
0,25 
0,25 
1 


0,25 
0,25 


12,5 


43,25 


16,75 


10       ,39 
11,5   129 


12,27 '43,5 
12        29 


1,5 
1,5 

3,5 

1,5 
1,5 
3,75 

32 

54 

12,5 

26 

51 

61,5 
0,5 
0,5 

7,5 
7,5 

18 

I 
57 

:i5,s 

21 

60 


0,75 


2,5 
19 


0,25  5,25 
*  24,65 
2,5    17,25 


24,50 

24,38 

26 

12,9 
2,3 
9,4 


0,75  18,25 
0,75  21 
1,5    18,75 


0,12 

0,12 

0,5 

0,5 

I 

0,25 

0,5 

0,57 

1 

0,25 

0,25 

0,25 
0,25 

e,5 

0,12 
0,5 
0,25 
0,12 
0,25 


15,63 

5,77 
5,4 
11 

1,6 
5,5 


3,12 


16,67 
18,78 
17,75 
12,25 
18,75 
15,5 
21,5 
23 
78 
7,6 
8,6 

17,25 
17 

3,05 

0,S 
2,25 
2,8 
29,88 
14,75 


15,63 

31,S2 
22,48 
24,5 

24,13 
19,5 


19,38 


C         106         3 

Besides  the  principles,  the  nature  of  which  has 
been  just  discussed,  ©thers  have  been  described  by 
chemists  as  belonging  to  the  vegetable  kingdom  :  thus 
a  substance,  somewhat  analogous  to  the  muscular 
fibre  of  animals,  has  been  detected  by  Vauquelin  in 
the  papaw ;  and  a  matter  similar  to  animal  gelatine  by 
Braconnot  in  the  mushroom  ;  but  in  this  place  it 
would  be  improper  to  dwell  upon  peculiarities  ;  my 
object  being  to  offer  such  general  views  of  the  consti- 
tution of  vegetables  as  may  be  of  use  to  the  agricul- 
turist. Some  distinctions  have  been  adopted  by  sys- 
tematical authors  which  I  have  not  entered  into,  be- 
cause they  do  not  appear  to  me  essential  to  this  enquiry. 
Dr.  Thomson,  in  his  elaborate  and  learned  system  of 
chemistry,  has  described  six  vegetable  substances, 
which  he  calls  mucus,  jelly,  sarcocol,  asparagin,  inu- 
lin,  and  ulmin.  He  states  that  mucus  exists  in  its 
purest  form  in  linseed  ;  but  Vauquelin  has  lately 
shewn,  that  the  mucilage  of  linseed  is,  in  its  essential 
characters,  analogous  to  gum  ;  but  that  it  is  combin- 
ed with  a  substance  similar  to  animal  mucus  :  vegeta- 
ble jelly.  Dr.  Thomson  himself  considers  as  a  modifi- 
cation  of  gum.  It  is  probable,  from  the  taste  of  sar- 
cocol, that  it  is  gum  combined  with  a  little  sugar. 
Inulin  is  so  analogous  to  starch,  that  it  is  probably  a 
variety  of  that  principle ;  ulmin  has  been  lately  shewn 
by  Mr.  Smithson  to  be  a  compound  of  a  peculiar  ex- 
tractive matter  and  potassa  ;  and  asparagin  is  proba- 
bly a  similar  combination.  If  slight  differences  in 
chemical  and  physical  properties  be  consided  as  suffi- 
cient to  establish  a  difference  in  the  species  of  vegeta- 
ble substances,  the  catalogue  of  them  might  be  enlar- 


ed  to  almost  any  extent.  No  two  compounds  procured 
from  different  vegetables  are  precisely  alike  j  and 
there  are  even  differences  in  the  qualities  of  the  same 
compound,  according  to  the  time  in  which  it  has  been 
collected,  and  the  manner  in  which  it  has  been  pre- 
pared :  the  great  use  of  classification  in  science  is  to 
assist  the  memory  5  and  it  ought  to  be  founded  upon 
the  similarity  of  properties  which  are  distinct,  charac- 
teristic, and  invariable. 

The  analysis  of  any  substance  containing  mix- 
tures of  the  different  vegetable  principles,  may  be 
made  in  such  a  manner  as  is  necessary  for  the  views 
of  the  agriculturist  with  facility.  A  given  quantity, 
say  200  grains,  of  the  substance  should  be  powdered, 
made  into  a  paste  or  mass,  with  a  small  quantity  of 
water,  and  kneaded  in  the  hands,  or  rubbed  in  a  mor- 
tar for  some  time  under  cold  water  ;  if  it  contain 
much  gluten,  that  principle  will  separate  in  a  coherent 
mass.  After  this  process,  whether  it  has  afforded 
gluten  or  not,  it  should  be  kept  in  contact  with  half  a 
pint  of  cold  water  for  three  or  four  hours,  being  oc- 
casionally rubbed  or  agitated  :  the  solid  matter  should 
be  separated  from  the  fluid  by  means  of  blotting  pa- 
per :  the  fluid  should  be  gradually  heated  ;  if  any 
flakes  appear,  they  are  to  be  separated  by  the  same 
means  as  the  solid  matter  in  the  last  process,  i.  e.  by 
filtration.  The  fluid  is  then  to  be  evaporated  to  dry- 
ness. The  matter  obtained  is  to  be  examined  by  ap- 
plying moist  paper,  tinged  with  red  cabbage  juice,  or 
violet  juice  to  it ;  if  the  paper  become  red,  it  contains 
acid  matter  j  if  it  become  green,  alkaline  matter  j  and 


C         108         3 

the  nature  of  the  acid  or  -jlkaline  matter  may  be 
known  by  applying  the  tests  described  page  97,98,100. 
If  the  solid  matter  be  sweet  to  the  taste,  it  must  be 
supposed  to  contain  sugar  ;  if  bitterish,  bitter  prin- 
ciple, or  extract ;  if  astringent,  tannin  :  and  if  it  be 
nearly  insipid,  it  must  be  principally  gum  or  mucilage. 
To  separate  gum  or  mucilage  from  the  other  princi- 
ples, alcohol  must  be  boiled  upon  the  solid  matter, 
which  will  dissolve  the  sugar  and  the  extract,  and 
leave  the  mucilage ;  the  weight  of  which  may  be  as- 
certained. •  . 

To  separate  sugar  and  extract,  the  alcohol  must 
be  evaporated  till  crytals  begin  to  fall  down,  which  are 
sugar ;  but  they  will  generally  be  coloured  by  some 
extract,  and  can  only  be  purified  by  repeated  solu- 
tions in  alcohol.  Extract  may  be  separated  from  su- 
gar by  dissolving  the  solid,  obtained  by  evaporation 
from  alcohol,  in  a  small  quantity  of  water,  and  boiling 
it  for  a  long  while  in  contact  with  the  air.  The  ex- 
tract will  gradually  fall  down  in  the  form  of  an  insolu- 
ble  power,  and  the  sugar  will  remain  in  solution. 

If  tannin  exist  in  the  first  solution  made  by  cold 
water,  its  separation  is  easily  effected  by  th(J  process 
described  page  83.  The  solution  of  isinglass  must  be 
gradually  added,  to  prevent  the  existence  of  an  excess 
of  animal  jelly  in  the  solution,  which  might  be  mista- 
ken  for  mucilage. 

When  the  vegetable  substance,  the  subject  of  ex- 
periment, will  afford  no  more  principles  to  cold  water^ 
it  must  be  exposed  to  boiling  water.  This  will  unite 
to  starch  if  there  be  any,  and  may  likewise  take  up 


t         109,        ] 

more  sugar,  extract,  and  tannin,  provided  they  be  in- 
timately combined  with  the  other  principles  of  the 
compound. 

The  mode  of  separating  starch  is  similar  to  that 
of  separating  mucilage. 

If  after  the  action  of  hot  water  any  thing  remain, 
the  action  of  boiling  afcohol  is  then  to  be  tried.  This 
will  dissolve  resinous  matter  ;  the  quantity  of  which 
may  be  known  by  evaporating  the  alcohol. 

The  last  agent  that  may  be  applied  is  ether, 
which  dissolves  elastic  gum,  though  the  application  is 
scarcely  ever  necessary  ;  for  if  this  principle  be  pre- 
sent, it  may  be  easily  detected  by  its  peculiar  qualities. 

If  any  fixed  oil  or  wax  exist  in  the  vegetable 
substance,  it  will  separate  during  the  process  of  boil- 
ing in  water,  and  may  be  collected.  Any  substance 
not  acted  upon  by  water,  alcohol,  or  ether,  must  be 
regarded  as  woody  fibre. 

If  volatile  oils  exist  in  any  vegetable  substances, 
it  is  evident  they  may  be  procured,  and  their  quantity 
ascertained,  by  distillation. 

When  the  quantity  of  fixed  saline,  alkaline,  met- 
allic, or  earthy  matter  in  any  vegetable  compound  is 
to  be  ascertained,  the  compound  must  be  decomposed 
by  heat,  by  exposing  it.  if  a  fixed  substance,  in  a  cru- 
cible, to  a  long  continued  red  heat  j  and  if  a  vola- 
tile substance,  by  passing  it  through  an  ignited  porce- 
lain tube.  The  nature  of  the  matter  so  produced, 
may  be  learnt  by  applying  the  tests  mentioned  in 
page  103, 


C       no       ] 

The  only  analyses  in  which  the  agricultural  che- 
mist can  often  wish  to  occupy  himself,  are  those  of 
substances  containing  principally  starch,  sugar,  gluten, 
oils,  mucilage,  albumen,  and  tannin. 

The  two  following  statements  will  afford  an  idea 
of  the  manner  in  which  the  results  of  experiments 
may  be  arranged. 

The  first  is  a  statement  of  the  composition  of 
ripe  peas,  deduced  from  experiments  made  by  Einhof ; 
the  second  are  of  the  products  afforded  by  oak  bark, 
deduced  from  experiments  conducted  by  myself. 

parts, 
3840  parts  of  ripe  peas  afford,  of  starch  1265 

Fibrous  matter  analogous  to  starch,  1 
with  the  coats  of  the  peas  J 

A  substance  analogous  to  gluten  550 

Mucilage  ...         -         249 

Saccharine  matter      -         -        -  81 

Albumen  .         .         -         -  66 

Volatile  matter  -         -         -         540 

Earthy  phosphates     -         -         -  1 1 

Loss 229 

1000  parts  of  dry  oak  bark,  from  a  small  tree 
deprived  of  epidermis,  contain. 

Of  woody  fibre  -         -         -      .  -         876 

—  tannin 57 

—  extract         -         -         -         -         -  31 

—  mucilage 18 

—  matter  rendered  insoluble  during  evapor-^ 

ation,  probably  a  mixture  of  albumen  J>  9 
and  extract  -         -         -        -     J 

—  loss,  partly  saline  matter  -        -        30 


C      111      ] 

To  ascertain  the  primary  elements  of  the  dif- 
ferent vegetable  principles,  and  the  proportions  in 
which  they  are  combined,  different  methods  of  analy- 
sis have  been  adopted.  The  most  simple  are  their  de- 
composition by  heat,  or  their  formation  into  new  pro- 
ducts by  combustion. 

When  any  vegetable  principle  is  acted  on  by  a 
strong  red  heat,  its  elements  become  newly  arranged. 
Such  of  them  as  are  volatile  are  expelled  in  the  gas- 
eous form  ;  and  are  either  condensed  as  fluids,  or  re- 
main permanently  elastic.  The  fixed  remainder  is 
either  carbonaceous,  earthy,  saline,  alkaline,  or  metal- 
lic matter. 

To  make  correct  experiments  on  the  decomposi- 
tion of  vegetable  substances  by  heat,  requires  a  com- 
plicated apparatus,  much  time  and  labour,  and  all  the 
resources  of  the  philosophical  chemist ;  but  such  re- 
sults as  are  useful  to  the  agriculturist  may  be  easily 
obtained.  The  apparatus  necessary,  is  a  green  glass 
retort,  attached  by  cement  to  a  receiver,  connected 
with  a  tube  passing  under  an  inverted  jar  of  known 
capacity,  filled  with  water.*  A  given  weight  of  the 
substance  is  to  be  heated  to  redness  in  the  retort  over 
a  charcoal  fire  ;  the  receiver  is  to  be  kept  cool,  and 
the  process  continued  as  long  as  any  elastic  matter  is 
generated.  The  condensible  fluids  will  collect  in  the 
receiver,  and  the  fixed  residuum  will  be  found  in  the 
retort.  The  fluid  products  of  the  distillation  of  vege- 
table substances  are  principally   water,    with    some 

*  Sec  Fig.  14. 


•C      112      3 

acetous  and  mucous  acids,  and  empyreumatic  oil,  or 
tar,  and  in  some  cases  ammonia.  The  gasses  are  car- 
bonic acid  gas,  carbonic  oxide,  and  carburetted  hydi*©- 
gene ;  sometimes  with  olefiant  gas,  and  hydrogene  ; 
and  sometimes,  but  more  rarely,  with  azote.  Car- 
bonic acid  is  the  only  one  of  those  gasses  rapidly  ab- 
sorbed by  water  ;  the  rest  are  inflammable ;  olefiant 
gas  burns  with  a  bright  white  light ;  carburetted  hy- 
drogene with  a  light  like  wax  ,  carbonic  oxide  with  a 
feeble,  blue  flame.  The  properties  of  hydrogene  and 
azote  have  been  described  in  the  last  Lecture.  The 
specific  gravity  of  carbonic  acid  gas,  is  to  that  of  air 
as  20.7  to  13.7,  and  it  consists  of  one  proportion  of 
carbon  11.4,  and  two  of  oxygene  30.  The  specific 
gravity  of  gaseous  oxide  of  carbon,  is  taking  the  same 
standard  13.2,  and  it  consists  of  one  proportion  of 
carbon,  and  one  of  oxygene. 

Xhe  specific  gravities  of  carburetted  hydrogene  and 
olefiant  gas  are  respectively  8  and  13  ;  both 'contain 
four  proportions  of  hydrogene  ;  the  first  contains  one 
proportion,  the  second  two  proportions  of  carbon. 

If  the  weight  of  the  carbonaceous  residuum  be 
added  to  the  weight  of  the  fluids  condensed  in  the 
receiver  and  they  be  subtracted  from  the  whole  weight 
of  the  substance,  the  remainder  will  be  the  weight  of 
the  gaseous  matter. 

The  acetous  and  mucous  acids,  and  the  ammonia 
formed  are  usually  in  very  small  quantitities  ;  and  by 
comparing  the  proportions  of  water  and  charcoal  with 
the  quantity  of  the  gasses,  taking  into  account  their 
qualides,  a  general  idea  may  be  formed  of  the  compo- 
sition of  the  substance.     The  proportions  of  the  ele- 


C      113      3 

ments  in  the  greater  number  of  the  vegetable  sub- 
stances which  can  be  used  as  food,  have  been  already 
ascertained  by  philosophical  chemists,  and  have  been 
stated  in  the  preceding  pages  ;  the  analysis  by  distil- 
lation may,  however,  in  some  cases,  be  useful  in  esti- 
mating the  powers  of  manures  in  a  manner  that  will 
be  explained  in  a  future  lecture. 

The  statements  of  the  composition  of  vegetable 
substances,  quoted  from  M.  M.  Gay  Lussac  and  Then- 
ard  were  obtained  by  these  philosophers  by  exposing 
the  substances  to  the  action  of  heated  hyper-oxy mu- 
riate of  potassa  j  a  body  that  consists  of  potassium, 
chlorine,  and  oxygene  j  and  which  afforded  oxygene  to 
the  carbon  and  the  hydrogene.  Their  experiments 
were  made  in  a  peculiar  apparatus,  and  required  great 
caution,  and  were  of  a  very  delicate  nature.  It  will 
not'  therefore  be  necessary  to  enter  upon  any  details 
of  them. 

It  is  evident  from  the  whole  tenor  of  the  state- 
ments which  have  been  made,  that  the  most  essential 
vegetable  substances  consist  of  hydrogene,  carbon, 
and  oxygene  in  different  proportions  generally  alone, 
but  in  some  few  cases  combined  with  azote.  The 
acids,  alkalies,  earths,  metallic  oxides,  and  saline  com- 
pounds, though  necessary  in  the  vegetable  ceconomy, 
must  be  considered  as  of  less  importance,  particularly 
in  their  relation  to  agriculture,  than  the  other  princi- 
ples :  and  as  it  appears  from  M.  de  Saussure's  table, 
and  from  other  experiments,  they  differ  in  the  same 
species  of  vegetable  when  it  is  raised  on  different  soils. 

Q 


[     114     J 

M.  M.  Gay  Lussac  and  Thenard  have  deduced 
three  propositions,  which  they  have  called  laws  from 
their  experiments  on  vegetable  substances.  The  first 
is,  "  that  a  vegetable  substance  is  always  acid  when- 
ever the  oxygene  it  contains  is  to  the  hydrogene  in  a 
greater  proportion  than  in  water/' 

The  second^  '^  that  a  vegetable  substance  is  always 
resinous  or  oily  or  spirituous  whenever  it  contains 
oxygene  in  a  smaller  proportion  to  the  hydrogene  than 
exists  in  water." 

The  third,  "  that  a  vegetable  substance  is  neither 
acid  nor  resinous  ;  but  is  either  saccharine  or  mucila- 
ginous, or  analogous  to  woody  fibre  or  starch,  when- 
ever the  oxygene  and  hydrogene  in  it  are  in  the  same 
proportions  as  in  water." 

New  experiments  upon  other  vegetable  sub- 
stances, besides  those  examined  by  M.  M.  Gay  Lussac 
and  Thenard,  are  required  before  these  interesting 
conclusions  can  be  fully  admitted.  Their  researches 
establish,  however,  the  close  analogy  between  several 
vegetable  compounds  differing  in  their  sensible  quali- 
ties, and  combined  with  those  of  other  chemists,  offer 
simple  explanations  of  several  processes  in  nature  and 
art,  by  which  different  vegetable  substances  are  con^ 
verted  into  each  other,  or  changed  into  new  com^ 
pounds. 

Gum  and  sugar  afford  nearly  the  same  elements 
by  analysis  :  and  starch  differs  from  them  only  in  con- 
taining a  little  more  carbon.  The  peculiar  properties 
of  gum  and  sugar  must  depend  chiefly  upon  the  dif- 
ferent arrangement,  or  degree  of  condensation  of  their 


elements  ;  and  it  would  be  natural  to  conceive  from 
the  composition  of  these  bodies,  as  well  as  that  of 
starch  that  all  three  would  be  easily  convertible  one 
into  the  other  ;  which  is  actually  the  case. 

At  the  time  of  the  ripening  of  corn,  the  saccha- 
rine matter  in  the  grain,  and  that  carried  from  the  sap 
vessels  into  the  grain,  becomes  coagulated,  and  forms 
starch.  And  in  the  process  of  malting,  the  converse 
change  occurs.  The  starch  of  grain  is  converted  into 
sugar.  As  there  is  a  little  absorption  of  oxygene,  and  a 
formation  of  carbonic  acid  in  this  case,  it  is  probable 
that  the  starch  loses  a  little  carbon,  which  combines 
with  the  oxygene  to  form  carbonic  acid ;  and  probably 
the  oxygene  tends  to  acidify  the  gluten  of  the  grain, 
and  thus  breaks  down  the  texture  of  the  starch  ;  gives 
a  new  arrangement  to  its  elements,  and  renders  it  so- 
luble in  water. 

Mr.  Cruikshank,  by  exposing  syrup  to  a  sub- 
stance named  phosphuret  of  lime,  which  has  a  great 
tendency  to  decompose  water,  converted  a  part  of  the 
sugar  into  a  matter  analogous  to  mucilage.  And  M. 
KirchhofF,  recently,  has  converted  starch  into  sugar  by 
a  very  simple  process,  that  of  boiling  in  very  diluted 
sulphuric  acid.  The  proportions  are  100  parts  of 
starch,  400  parts  of  water,  and  1  part  of  sulphuric 
acid  by  weight.  This  mixture  is  to  be  kept  boiling 
for  40  hours  ;  the  loss  of  water  by  evaporation  being 
supplied  by  new  quantities.  The  acid  is  to  be  neu- 
tralized by  lime ;  and  the  sugar  crystallized  by  cool* 
ing.  This  experiment  has  been  tried  with  success  by 
many  persons.     Dr.  Tuthill,  from  a  pound  and  a  half 


[  116  J 

of  potatoe  starch,  procured  a  pound  and  a  quarter  of 
crystalline,  brown  sugar  ;  which  he  conceives  posses- 
sed properties  intermediate  between  cane  sugar,  and 
grape  sugar. 

It  is  probable  that  the  conversion  of  starch  into 
sugar  is  effected  merely  by  the  attraction  of  the  acid 
for  the  elements  of  sugar  ;  for  various  experiments 
have  been  made,  which  prove  that  the  acid  is  not  de- 
composed, and  that  no  elastic  matter  is  set  free  ;  pro- 
bably the  colour  of  the  sugar  is  owing  to  the  disen- 
gagement, or  new  combination  of  a  little  carbon,  the 
slight  excess  of  which,  as  has  been  just  stated,  consti- 
tutes the  only  difference  perceptible  by  analysis  be- 
tween sugar  and  starch. 

M.  Bouillon  la  Grange,  by  slightly  roasting  starch 
has  rendered  it  soluble  in  cold  water ;  and  the  solu- 
tion evaporated  afforded  a  substance,  having  the 
characters  of  mucilage. 

Gluten  and  albumen  differ  from  the  other  vege- 
table products,  principally  by  containing  azote.  When 
gluten  is  kept  long  in  water  it  undergoes  fermenta- 
tion ;  ammonia  (which  contains  its  azote)  is  given  off 
with  acetic  acid  :  and  a  fatty  matter,  and  a  substance 
analogous  to  woody  fibre  remain. 

Extract,  tannin,  and  gallic  acid,  when  their  solu- 
tions are  long  exposed  to  air,  deposit  a  matter  similar 
to  woody  fibre  j  and  the  solid  substances  are  render- 
ed analogous  to  woody  fibre  by  slight  roasting  ;  and  in 
these  cases  it  is  probable  that  part  of  their  oxygene 
and  hydrogene  is  separated  as  water. 


[         117        ] 

All  the  other  vegetable  principles  differ  from  the 
vegetable  acids  in  containing  more  hydrogene  and  car- 
bon, 'or  less  oxygene ;  many  of  them  therefore  are 
easily  converted  into  vegetable  acids  by  a  mere  sub- 
traction of  some  proportions  of  hydrogene.     The  ve- 
getable acids,  for  the  most  part,  are  convertible  into 
each  other  by  easy  processes.     The  oxalic  contains 
most  oxygene  ;  the  acetic  the  least :  and  this  last  sub- 
stance is  easily  formed  by  the  distillation  of  other  ve- 
getable substances,  or  by  the  action  of  the  atmosphere 
on  such  of  them  as  are  soluble  in  water ;  probably 
by  the  mere  combination  of  oxygene  with  hydrogene 
and  carbon,  or  in  some  cases  by  the  subtraction  of  a 
portion  of  hydrogene. 

Alcohol,  or  spirits  of  wine,  has  been  often  men- 
tioned in  the  course  of  these  Lectures.  This  sub- 
stance was  not  described  amongst  the  vegetable  princi- 
ples, because  it  has  never  been  found  ready  formed  in 
the  organs  of  plants.  It  is  procured  by  a  change  in 
the  principles  of  saccharine  matter,  in  a  process  called 
vinous  fermentation. 

The  expressed  juice  of  the  grape  contains  sugar^ 
mucilage,  gluten,  and  some  saline  matter,  principally 
composed  of  tartaric  acid  :  when  this  juice,  or  musty 
as  it  is  commonly  called,  is  exposed  to  the  tempera- 
ture of  about  70°,  the  fermentation  begins ;  it  be- 
comes thick  and  turbid  ;  its  temperature  increases,  and 
carbonic  acid  gas  is  disengaged  in  abundance.  In  a 
few  days  the  fermentation  ceases ;  the  solid  matter 
that  rendered  the  juice  turbid  falls  to  the  bottom,  and 
it  clears  j  the  sweet  taste  of  the  fluid  is  in  great  mea- 
sure destroyed,  and  it  is  become  spirituous. 


C      118      2 

Fabroni  has  shewn  that  the  gluten  in  must  is 
essential  to  fermentation ;  and  that  chemist  has  made 
saccharine  matter  ferment,  by  adding  to  its  solution 
in  water,  common  vegetable  gluten  and  tartaric  acid. 
Gay  Lussac  has  demonstrated  that  must  will  not  fer- 
ment when  freed  from  air  by  boiling,  and  placed  out 
of  the  contact  of  oxygene ,  but  that  fermentation  be- 
gins as  soon  as  it  is  exposed  to  the  oxygene  of  air,  a 
little  of  that  principle  being  absorbed  ;  and  that  it  then 
continues  independent  of  the  presence  of  the  atmos- 
phere. 

In  the  manufacture  of  ale  and  porter,  the  sugar 
formed  during  the  germination  of  barley  is  made  to 
ferment  by  dissolving  it  in  water  with  a  little  yeast, 
which  contains  gluten  in  the  state  proper  for  produc- 
ing fermentation,  and  exposing  it  to  the  requisite  tem- 
perature ;  carbonic  acid  gas  is  given  off  as  in  the 
fermentation  of  must,  and  the  liquor  gradually  be- 
comes spirituous. 

Similar  phaenomena  occur  in  the  fermentation  of 
the  sugar  in  the  juice  of  apples,  and  other  ripe  fruits. 
It  appears  that  fermentation  depends  entirely  upon  a 
new  arrangement  of  the  elements  of  sugar ;  part  of 
the  carbon  uniting  to  oxygene  to  form  carbonic  acid, 
and  the  remaining  carbon,  hydrogene,  and  oxygene 
combining  as  alcohol ;  and  the  use  of  the  gluten  or 
yeast,  and  the  primary  exposure  to  air  seems  to  be  to 
occasion  the  formation  of  a  certain  quantity  of  car- 
bonic acid ;  and  this  change  being  once  produced  is 
continued ;  its  agency  may  be  compared  to  that  of  a 
spark  in  producing  the  inflammation  of  gunpowder  ^ 


C  "9         ] 

the  increase  of  temperature  occasioned  by  the  forma- 
tion of  one  quantity  of  carbonic  acid  occasions  the 
combination  of  the  elements  of  another  quantity. 

The  results  obtained  by  different  chemists  in  ex- 
periments on  the  analysis  of  alcohol  differ  so  much, 
that  no  general  conclusions  can  be  drawn  from  them. 
If  it  be  supposed  that  one  proportion  of  carbonic  acid 
is  formed  in  the  fermentation  of  sugar  ;  then  accord- 
ing to  Dr.  Thomson's  analysis  of  sugar,  which  gives 
its  composition  as  3  proportions  of  carbon,  4  of  oxy- 
gene,  and  8  of  hydrogene,  alcohol  would  consist  of 
2  proportions  of  carbon,  2  of  oxygene,  and  8  of  hy- 
drogene ;  and  it  might  be  considered  as  containing  the 
same  elements  as  two  proportions  of  olefiant  gas,  with 
two  proportions  of  oxygene. 

Alcohol  in  its  purest  known  form,  is  a  highly 
inflammable  liquid,  of  specific  gravity  796,  at  the 
temperature  of  60° ;  it  boils  at  about  170o  Fahrenheit. 
This  alcohol  is  obtained  by  repeated  distillation  of  the 
strongest  common  spirit  from  the  salt  called  by  che- 
mists muriate  of  lime,  it  having  been  previously  heat- 
ed red  hot. 

The  strongest  alcohol  obtained  by  the  distillation 
of  spirit  without  salts,  has  seldom  a  less  specific  gravi- 
ty than  825  at  60";  and  it  contains,  according  to 
Lowitz's  experiments,  89  parts  of  the  alcohol  of  796, 
and  11  parts  of  water.  The  spirit  established  2iS  proof 
spirit  by  act  of  parliament  passed  in  1762,  ought  to 
have  the  specific  gravity  of  916;  and  this  contains 
nearly  equal  weights  of  pure  alcohol  and  water. 


C  120  ] 

The  alcohol  in  fermented  liquors  is  in  combina- 
tion with  water,  colouring  matter,  sugar,  mucilage, 
and  the  vegetable  acids.  It  has  been  often  doubted 
whether  it  can  be  procured  by  any  other  process  than 
distillation ;  and  some  persons  have  even  supposed 
that  it  is  formed  by  distillation.  The  recent  experi- 
ments of  Mr.  Brande  are  conclusive  against  both 
these  opinions.  That  gentleman  has  shewn  that  the 
colouring  and  acid  matter  in  wines  may  be,  for  the 
most  part,  separated  in  a  solid  form  by  the  action  of  a 
solution  of  sugar  of  lead  (acetate  of  lead),  and  that  the 
alcohol  may  be  then  obtained  by  abstracting  the  water 
by  means  of  hydrate  of  potassa  or  muriate  of  lime, 
without  artificial  heat. 

The  intoxicating  powers  of  fermented  liquors 
depend  on  the  alcohol  that  they  contain ;  but  their 
action  on  the  stomach  is  modified  by  the  acid,  saccha- 
rine, or  mucilaginous  substances  they  hold  in  solu- 
tion. Alcohol  probably  acts  with  more  efficacy  when 
it  is  most  loosely  combined  ;  and  its  energy  seems  to 
be  impaired  by  union  with  large  quantities  of  water, 
or  with  sugar  or  acid,  or  extractive  matter. 

The  following  table  contains  the  results  of  Mr. 
Brande's  experiments  on  the  quantity  of  alcohol  of 
825  at  60°,.  in  different  fermented  liquors. 


121 


1 


Proportion  of 

Proportion  of 

Wine. 

Alcohol,   per 

Wine. 

Alcohol,    per 

Cent,  by  Mea- 

Cent, by  Mea- 

sure. 

sure. 

Port       -        .        - 

31,40 

White  Hermitage    - 

17,43 

Ditto      - 

22,30 

Red  Hermitage 

12,32 

Ditto      -         -         - 

23,39 

Hock       - 

14,37 

Ditto       - 

23,71 

Ditto 

8,88 

Ditto      '- 

24,29 

Vinde  Grave  - 

12,80 

Ditto      -        ,- 

25,83 

Frontignac 

12,79 

Madeira 

19,34 

Coti  Roti 

12.32 

Ditto 

21,40 

Rousiilon 

17,26 

Ditto 

23,93 

Cape  Madeira 

18,11 

Ditto 

34,42 

Cape  Muschat 

18,25 

Sherry    - 

18,25 

Constantia 

19,75 

Ditto 

18,79 

Tent 

13,30 

Ditto 

19,81 

Sheraaz 

15,52 

Ditto 

19,83 

Syracuse 

15.23 

Claret     - 

12,91 

Nice        .         -         - 

14,63 

Ditto 

14,08 

Tokay    - 

9,88 

Ditto 

16,32 

Raisin  Wine    - 

25.T7 

Calcavella 

18.10 

Grape  Wine    - 

18.11 

Lisbon     - 

18,94 

Currant  Wine 

20.55 

Malaga    - 

17,26 

Gooseberry  Wme    - 

11,84 

Bucellas 

18,49 

Elder  Wine     - 

'       9,87 

Red  Madeira  - 

18.40 

Cyder     - 

9,87 

Malmsey  Madeira    - 

16,40 

Perry      - 

9,87 

Marsala 

25.87 

Brown  Stout  - 

6,80 

Ditto 

17,26 

Ale          -         -         - 

8,88 

Red  Champagne 

11,30 

Brandy   - 

53,39 

White  Champagne  - 

12,80 

Rum 

53,68 

Burgundy 

14,53 

Hollands 

51,60 

Ditto      .         .         - 

11,95 

The  spirits  distilled  from  different  fermented 
liquors  differ  in  their  flavour  :  for  peculiar  odorous 
matter,  or  volatile  oils,  rise  in  most  cases  with  the  al- 
cohol. The  spirit  from  malt  usually  has  an  empy- 
reumatic  taste  like  that  of  the  oil,  formed  by  the  dis- 
tillation of  vegetable  substances.  The  best  brandies 
seem  to  owe  their  flavour  to  a  peculiar  oily  matter, 
formed  probably  by  the  action  of  the  tartaric  acid  on 
alcohol ;  and  rum  derives  its  characteristic  taste  from 
a  principle  in  the  sugar  cane.  All  the  common  spirits 
may,  I  find,  be  deprived  of  their  peculiar  flavour  by 
repeatedly  digesting  them  with  a  mixture  of  well  burnt 


t         122         2 

charcoal  and  quicklime  ;  they  then  afford  pure  alco- 
hol by  distillation.  The  cognac  brandies,  I  find,  con- 
tain vegetable  prussic  acid,  and  their  flavour  may  be 
imitated  by  adding  to  a  solution  of  alcohol  in  water  of 
the  same  strength,  a  few  drops  of  the  ethereal  oil  of 
wine  produced  during  the  formation  of  ether,*  and  a 
similar  quantity  of  vegetable  prussic  acid  procured 
from  laurel  leaves  or  any  bitter  kernels. 

I  have  mentioned  eiber  in  the  course  of  this  Lec- 
ture ;  this  substance  is  procured  from  alcohol  by  distil- 
ling a  mixture  of  equal  parts  of  alcohol  and  sulphuric 
acid.  It  is  the  lightest  known  liquid  substance,  being 
of  specific  gravity  632  at  60°.  I|  i&  very  volatile,  and 
rises  in  vapour  even  by  the  heat  of  the  body.  It  is 
highly  inflammable.  In  the  formation  of  ether  it  is 
most  probable  that  carbon  and  the  elements  of  water 
are  separated  from  the  alcohol,  and  that  ether  differs 
from  alcohol  in  containing  less  oxygene  and  carbon  ; 
but  its  composition  has  not  yet  been  accurately  ascer- 
tained.   Like  alcohol  it  possesses  intoxicating  powers. 

A  number  of  the  changes  taking  place  in  the  ve- 
getable principles  depend  upon  the  separation  of  oxy* 
gene  and  hydrogene  as  water  from  the  compound  ; 
but  there  is  one  of  very  great  importance,  in  which  a 
new  combination  of  the  elements  of  water  is  the  prin- 
cipal operation.  This  is  in  the  manufacture  of  bread. 
When  any  kind  of  flour,  which  consists  principally  of 


*  In  tbe  process  of  the  distillation  of  alcohol  and  sulphuric  acid  after  the  ether 
is  procured ;  by  a  higher  degree  of  heat,  a  yellow  fluid  is  produced,  which  is  the 
substance  in  question.    It  has  a  fragrant  smell  and  an  agreeable  taste. 


[  123         ] 

starch,  is  made  into  a  paste  with  water,  and  immedi- 
ately and  gradually  heated  to  about  440°,  it  increases 
in  werght,  and  is  found  entirely  altered  in  its  proper- 
ties ;  it  has  lost  its  solubility  in  water,  and  its  power 
of  being  converted  into  sugar.  In  this  state  it  is  un- 
leavened bread. 

When  the  flour  of  corn  or  the  starch  of  potatoes, 
mixed  with  boiled  potatoes,  is  made  into  a  paste  with 
water,  kept  warm,  and  suffered  to  remain  30  or  40 
hours,  it  ferments,  carbonic  acid  gas  is  disengaged 
from  it,  and  it  becomes  filled  witli  globules  of  elastic 
fluid.  In  this  state  it  is  raised  dough,  and  affords  by 
baking,  leavened  bread ;  but  this  bread  is  sour  and 
disagreeable  to  the  taste ;  and  leavened  bread  for  use 
is  made  by  mixing  a  little  dough,  that  has  fermented, 
with  new  dough,  and  kneading  them  together,  or  by 
kneading  the  bread  with  a  small  quantity  of  yeast. 

In  the  formation  of  wheaten  bread  more  than  1-4 
of  the  elements  of  water  combine  with  the  flour ; 
more  water  is  consolidated  in  the  formation  of  bread 
from  barley,  and  still  more  in  that  from  oats ;  but 
the  .gluten  in  wheat,  being  in  much  larger  quantity 
than  in  other  grain,  seems  to  form  a  combination  with 
the  starch  and  water,  which  renders  wheaten  bread 
more  digestible  than  the  other  species  of  bread. 

The  arrangement  of  many  of  the  vegetable  prin- 
ciples in  the  different  parts  of  plants  has  been  inciden- 
tally mentioned  in  this  Lecture ;  but  a  more  particular 
statement  is  required  to  afford  just  views  of  the  rela- 
tion between  their  organization  and  chemical  constitu- 
tion, which  is  an  object  of  great  importance.    The 


C         124         ] 

tubes  and  hexagonal  cells  in  the  vascular  system  of 
plants  are  composed  of  woody  fibre ;  and  when  they 
are  not  filled  with  fluid  matter  they  contain  some  of 
the  solid  materials  which  formed  a  constituent  part  of 
the  fluids  belonging  to  them. 

In  the  roots,  trunk,  and  branches,  the  bark,  al- 
burnum, and  heartwood,  the  leaves  and  flowers  ;  the 
great  basis  of  the  solid  parts  Js  woody  fibre.  It  forms 
by  far  the  greatest  part  of  the  heart  wood  and  bark  ; 
there  is  less  in  the  alburnum,  and  still  less  in  the  leaves 
and  flowers.  The  alburnum  of  the  birch  contains  so 
much  sugar  and  mucilage,  that  it  is  sometimes  used 
in  the  North  of  Europe  as  a  substitute  for  bread.  The 
leaves  of  the  cabbage,  broccoli,  and  seacale,  contain 
much  mucilage,  a  little  saccharine  matter  and  a  little 
albumen.  From  a  1 OOO  parts  of  the  leaves  of  com- 
mon cabbage  I  obtained  41  parts  of  mucilage,  24  of 
sugar,  and  8  of  albuminous  matter. 

In  bulbous  roots,  and  sometimes  in  common 
roots,  a  large  quantity  of  starch,  albumen,  and  mucil- 
age, are  often  found  deposited  in  the  vessels ;  and 
they  are  most  abundant  after  the  sap  has  ceased  to 
flow  :  and  afford  a  nourishment  for  the  early  shoots 
made  in  spring.  The  potatoe  is  the  bulb  that  contains 
the  largest  quantity  of  soluble  matter  in  its  cells  and 
vessels  ;  and  it  is  of  most  importance  in  its  appli- 
cation as  food.  Potatoes  in  general  afford  from  '  to  4 
their  weight  of  dry  starch.  From  100  parts  of  the 
common  Kidney  potatoes^  Dr.  Pearson  obtained  from 
32  to  28  parts  of  meal,  which  contained  from  23  to 
20  of  starch  and  mucilage :  and  100  parts  of  the  Ap- 


C  125         ] 

pie  potatoe  in  various  experiments,  afforded  me  from 
18  to  20  parts  of  pure  starch.  From  five  pounds  of 
the  variety  of  the  potatoe  called  Captain  hart^  Mr. 
Skrimshire,  jun.  obtained  12  oz.  of  starch,  from  the 
same  quantity  of  the  Rough  red  potatoe  104  oz.,  from 
the  Moult  on  white  11t,  from  the  Yorkshire  kidney 
10^  oz.,  from  Hundred  eyes  9  oz.,  from  Purple  red  81, 
from  Ox  noble  8t.  The  other  soluble  substances  in 
the  potatoe  are  albumen  and  mucilage. 

From  the  analysis  of  EinhofFit  appears  that  7680 
parts  of  potatoes  afford 

Of  starch  -         -         -         -         1153 

— •  Fibrous  matter  analogous  to  starch    540 

—  Albumen    -         -         .         -  107 

—  Mucilage  in  the  state  of  a  saturated") 


solution   .        .        .         .         ^^^^ 


2112 
So  that  a  fourth  part  of  the  weight  of  the  potatoe  at 
least  may  be  considered  as  nutritive  matter. 

The  turnip,  carrot,  and  parsnip,  afford  principally 
saccharine,  mucilaginous,  and  extractive  matter.  I 
obtained  from  1000  parts  of  common  turnips  7  parts 
of  mucilage,  34  of  saccharine  matter,  and  nearly  1 
part  of  albumen.  1000  parts  of  carrots  furnished 
95  parts  of  sugar.  3  parts  of  mucilage,  and  ^  part  of 
extract ;  1000  parts  of  parsnip  afforded  90  parts  of 
saccharine  matter,  and  9  parts  of  mucilage.  The 
Walcheren  or  white  carroty  gave  in  1000  parts,  98 
parts  of  sugar,  2  parts  of  mucilage,  and  1  of  extract. 


t  126  3 

Fruits,  In  the  organization  of  their  soft  parts, 
approach  to  the  nature  of  bulbs.  They  contain  a  cer- 
tain quantity  of  nourishment  laid  up  in  their  cells  for 
the  use  of  the  embryon  plant ;  mucilage,  sugar,  starch 
are  found  in  many  of  them  often  combined  with  vege- 
table acids.  Most  of  the  fruit  trees  common  in  Bri- 
tain have  been  naturalized  on  account  of  the  saccha- 
rine matter  they  contain,  which^  united  to  the  vegeta- 
ble acids  and  mucilage,  renders  them  at  once  agreea- 
ble to  the  taste  and  nutritive. 

The  value  of  fruits  for  the  manufacture  of  fer- 
mented liquors  may  be  judged  of  from  the  specific 
gravity  of  their  expressed  juices.  The  best  cyder  and 
perry  are  made  from  those  apples  and  pears  that  af- 
ford the  densest  juices  ;  and  a  comparison  between 
different  fruits  may  be  made  with  tolerable  accuracy 
by  plunging  them  together  into  a  saturated  solution  of 
salt,  or  a  strong  solution  of  sugar ;  those  that  sink 
deepest  will  afford  the  richest  juice. 

Starch  or  coagulated  mucilage  forms  the  greatest 
part  of  the  seeds  and  grains  used  for  food  ;  and  they 
are  generally  combined  with  gluten,  oil,  or  albumin- 
ous matter.  In  corn,  with  gluten,  in  peas  and  beans, 
with  albuminous  matter ;  and  in  rape-seed,  hemp- 
seed,  linseed,  and  the  kernels  of  most  nuts,  with  oils. 

I  found  lOO  parts  of  good  full  grained  wheat 
sown  in  autumn  to  afford 

Of  Starch      -         -         -        77 
—  Gluten     -         -         •         19 
100  parts  of  wheat  sown  ik  spring. 

Of  starch       *        -         •         70 
*— Gluten     ...        24 


[  127         ]         ' 

100  parts  of  Barbary  wheat, 

Of  starch       -         -         -         47 

—  Gluten      -  <         23 
100  parts  of  Sicilian  wheat. 

Of  starch       -         .         .         75 

—  Gluten     -         -         .         21 

I  have  examined  diiferent  specimens  of  North 
American  wheat,  all  of  them  have  contained  rather 
more  gluten  than  the  British.  In  general  the  wheat 
of  warm  climates  abounds  more  in  gluten,  and  in  in- 
soluble parts  j  and  it  is  of  greater  specific  gravity, 
harder,  and  more  difficult  to  grind. 

The  wheat  of  the  south  of  Europe,  in  conse- 
quence of  the  larger  quantity  of  gluten  it  contains,  is 
peculiary  fitted  for  making  macaroni,  and  other  pre- 
parations of  flower  in  which  a  glutinous  quality  is  con-  'S 
sidered  as  an  excellence. 

In  some  experiments  made  on  barley,  I  obtained 
from  100  parts  of  full  and  fair  Norf®lk  barley. 
Of  Starch      ...         79 

—  Gluten     .        ,        ^  6 

—  Husk        -         .        -  8 
The  remaining  7  parts  saccharine  matter. 

EinhoiF  has  published  a  minute  analysis  of  barley 
meal.     He  found  in  3840  parts. 

Of  volatile  matter       .         -         .         360 

—  Albumen      ....  44 

—  Saccharine  matter  -        *        200 

—  Mucilage       ....         176 

—  Phosphate  of  lime,  with  some  albumen  9 

—  Gluten  *        -        -        -         135 


C      128     y 

Of  Husk,  with  some  gluten  and  starch  260 
■ —  Starch  not  quite  free  from  gluten     2580 

—  Loss 78 

Rye  afforded  to  Einhoff,  in  3840  parts  ;  2520 

meal,  930  husk,  and  390  moisture  j  and  the  same 
quantity  of  meal  analysed  gave. 

Of  Starch  .         -         -         .         2345 

—  Albumen     -         -         -         -  126 
~ — Mucilage     -         -         -         -           426 

—  Saccharine  matter  -         -  126 

—  Gluten  not  dried  -         -  364 
Remainder  husk  and  loss. 

I  obtained  from  100  parts  of  rye,  grown  in  Suf- 
folk, 61  parts  of  starch,  and  5  parts  of  gluten. 

100  parts  of  oats,  from  Sussex,  afforded  me  59 
parts  of  starch,  6  of  gluten,  and  2  of  saccharine  mat- 
ter, 

1000  parts  of  peas,  grown  in  Norfolk,  afforded 
me  501  parts  of  starch,  22  parts  of  saccharine  matter, 
35  parts  of  albuminous  matter  and  16  parts  of  ex- 
tract, which  became  insoluble  during  evaporation  of 
the  saccharine  fluid. 

From  3840  parts  of  marsh  beans  CViciafabaJy 
Einhoff  obtained, 

Of  Starch         -         -         -         -         1312 

—  Albumen     .         -         -         -  31 

—  other  matters  which  may  be  con-"] 

ceived  nutritive :  such  as  gum-  j 

1       r^  ^1204 

my,  starchy,  fibrous  matter  an-  r 

alogous  to  animal  matter  J 


C  129  ] 

The  same  quantity  of  kidney  beans  {Fhaseolus 
'vulgaris)  afforded, 

Of  matter  analogous  to  starch     -         1 805 

—  Albumen  and  matter  approaching  1 

to  animal  matter  in  its  nature    j    ^"^^ 

—  Mucilage     -         -         -         -  799 
From  3840  parts  of  lentiles  he  obtained  1260 

parts  of  starch,  and  14/33  of  a  matter  analogous  to 
animal  matter. 

The  matter  analogous  to  animal  matter  is  des- 
cribed by  Einhoff ;  as  a  glutinous  substance  insoluble 
in  water  ;  soluble  in  alcohol  when  dry,  having  the  ap- 
pearance of  glue  j  probably  a  peculiar  modification  of 
gluten. 

From  16  parts  of  hemp-seeds  Bucholz  obtained 
3  parts  of  oil,  Si  parts  of  albumen,  about  1  -  of  sac- 
charine and  gummy  matter.  The  insoluble  husks 
and  coats  of  the  seeds  weighed  6^  parts. 

The  different  parts  of  flowers  contain  different 
substances  :  the  pollen,  or  impregnating  dust  of  the 
date,  has  been  found  by  Fourcroy  and  Vauquelin  to 
contain  a  matter  analogous  to  gluten,  and  a  soluble 
extract  abounding  in  malic  acid.  Link  found  in  the 
pollen  of  the  hazle  tree,  much  tannin  and  gluten. 

Saccharine  matter  is  found  in  the  nectarium  of 

flowers,  or  the  receptacles  within  the  corolla,  and  by 

tempting  the  larger  insects  into  the  flowers,  it  renders 

the  work  of  impregnation  more  secure ;  for  the  pollen 

is  often  by  their  means  applied  to  the  stigma ;  and 

this  is  particularly  the  case  when  the  male  and  female 

organs  are  in  different  flowers  or  different  plants. 

s 


A. 


[      ISO      3 

It  has  been  stated  that  the  fragrance  of  flowers 
depends  upon  the  volatile  oils  they  contain ;  and  these 
oils,  by  their  constant  evaporation,  surround  the 
flower  with  a  kind  of  odorous  atmosphere ;  which,  at 
the  same  time  that  it  entices  larger  insects,  may  pro- 
bably preserve  the  parts  of  fructification  from  the  ra- 
vages of  the  smaller  ones.  Volatile  oils,  or  odorous 
substances,  seem  particularly  destructive  to  these  mi- 
nute insects  and  animalcules  which  feed  on  the  sub- 
stance of  vegetables  ;  thousands  of  aphides  may  be 
usually  seen  in  the  stalk  and  leaves  of  the  rose  ;  but 
none  of  them  are  ever  observed  on  the  flower.  Cam- 
phor is  used  to  preserve  the  collections  of  naturalists. 
The  woods  that  contain  aromatic  oils  are  remarked 
for  their  indestructibility ;  and  for  their  exemption 
from  the  attacks  of  insects  :  this  is  particularly  the 
case  with  the  cedar,  rose- wood,  and  cypress.  The 
gates  of  Constantinople,  which  were  made  of  this  last 
wood,  stood  entire  from  the  time  of  Constantine,  their 
founder,  to  that  of  Pope  Eugene  IV.  a  period  of  1 100 
years. 

The  petals  of  many  flowers  afford  saccharine  and 
mucilaginous  matter.  The  white  lily  yields  mucilage 
abundantly  ;  and  the  orange  lily  a  mixture  of  mucil- 
age and  sugar ;  the  petals  of  the  convolvulus  afford 
sugar,  mucilage,  and  albuminous  matter. 

The  chemical  nature  of  the  colouring  matters  of 
flowers  has  not  as  yet  been  subject  to  any  very  accu- 
rate observation.  These  colouring  matters,  in  gen- 
eral, are  very  transient,  particularly  the  blues  and 
reds  y  alkalies  change  the  colours  of  most  flowers  to 
green,  and  acids  to  red.     An  imitation  of  the  colour- 


C      131      D 

ing  matter  may  be  made  by  digesting  solutions  of  gall- 
nuts  with  chalk:  a  green  fluid  is  obtained,  which  be- 
comes red  by  the  action  of  an  acid;  and  has  its  green 
colour  restored  by  means  of  alkalies. 

The  yellow  colouring  matters  of  flowers  are  the 
most  permanent;  the  carthamus  contains  a  red  and  a 
yellow  colouring  matter;  the  yellow  colouring  matter 
is  easily  dissolved  by  water,  and  from  the  red,  rouge 
is  prepared  by  a  process  which  is  kept  secret. 

The  same  substances  as  exist  in  the  solid  parts  of 
plants  are  found  in  their  fluids,  with  the  exception  of 
woody  fibre.  Fixed  and  volatile  oils  containing  resin 
or  camphor,  or  analogous  substances  in  solution  exist 
in  the  cylindrical  tubes  belonging  to  a  number  of 
plants.  Different  species  of  Euphorbia  emit  a  milky 
juice,  which  when  exposed  to  air  deposit  a  substance 
analogous  to  starch,  and  another  similar  to  gluten. 

Opium,  gum  elastic,  gamboge^  the  poisons  of  the 
Upas  Antiar  and  Tieute,  and  other  substances  that 
exude  from  plants,  may  be  considered  as  peculiar 
juices  belonging  to  appropriate  vessels. 

The  sap  of  plants,  in  general,  is  very  compound 
in  its  nature;  and  contains  most  saccharine,  mucilagin- 
ous, and  albuminous  matter  in  the  alburnum;  and 
most  tannin  and  extract  in  the  bark.  The  cambium, 
which  is  the  mucilaginous  fluid  found  in  trees  between 
the  wood  and  the  bark,  and  which  is  essential  to  the 
formation  of  new  parts,  seems  to  be  derived  from  these 
two  kinds  of  sap;  and  probably  is  a  combination  of 
the  mucilaginous  and  albuminous  matter  of  one,  with 
the  astringent  matter  of  the  other,  in  a  state  fitted  to 
become  organized  by  the  separation  of  its  watery  parts 


■%, 


C  132         ] 

The  alburnous  saps  of  some  trees  have  been  che- 
mically examined  by  Vauquelin.  He  found  in  those 
of  the  elm,  beech,  yoke  elm,  hornbeam  and  birch,  ex- 
tractive and  mucilaginous  matter,  acetic  acid  combin- 
ed with  potassa  or  Ume.  The  solid  matter  afforded 
by  their  evaporation  yielded  an  ammoniacal  smell,  pro- 
bably owing  to  albumen;  the  sap  of  the  birch  afforded 
saccharine  matter. 

Deyeux  in  the  sap  of  the  vine  and  the  yoke  elm 
has  detected  a  matter  analogous  to  the  curd  of  milk. 
I  found  a  substance  similar  to  albumen  in  the  sap  of 
the  walnut  tree. 

I  found  the  juice  which  exudes  from  the  vessels 
of  the  marshmallow  when  cut,  to  be  a  solution  of 
mucilage. 

The  fluids  contained  in  the  sap  vessels  of  wheat 
and  barley,  afforded  in  some  experiments  which  I  made 
on  them,  mucilage,  sugar,  and  a  matter  which  coag- 
ulated by  heat;  which  last  was  most  abundant  in  wheat. 
The  following  table  contains  a  statement  of  the 
quantity  of  soluble  or  nutritive  matters  contained  in 
varieties  of  the  different   substances  that  have  been 
mentioned,  and  of  some  others  which  are  used  as  arti- 
cles of  food,  either  for  man  or  cattle.     The  analyses 
are  my  own;  and  were  conducted  with  a  view  to  a 
knowledge  of  the  general  nature  and  quantity  of  the 
products,  and  not  of  their  intimate  chemical  composi- 
tion.    The  soluble  matters  afforded  by  the  grasses, 
except  that  from  the  fiorin  in  winter,  were  obtained 
by  Mr.   Sinclair,  gardener  to  the  duke  of  Bedford, 
from  given  weights  of  the  grasses  cut  when  the  seeds 
were  ripe;  they  were  sent  to  me  by  his  Grace's  desire 


# 


c 


133 


] 


for  chemical  examination;  and  form  part  of  the  results 
of  an  important  and  extensive  series  of  experiments  on 
grasses,  made  by  direction  of  the  Duke,  at  Woburn 
Abbey,  the  full  details  of  which  I  shall  hereafter  have 
the  pleasure  of  stating. 

Table  of  the  Quantities  of  soluble  or  nutritive  Matters 
afforded  by  1000  parts  of  different  vegetable  Sub- 
stances, 


Cm     d 

W    (U   c 

°l 

w 

3 

iJS.2 

>>  « 

u 

*j 

U3 

15  B,  *k 

•S'S 

o 

< 

6  SS 

-'Vegetables  or  vegetable 

H 

oi 

o-t 

Substance. 

.S5 

l^ 

3 

-c  2. 

u 

0 

^U 

^g 

$, 

Middlesex  wheat,  average 

crop 

955 

765 

— 

190 

Spring  wheat 

940 

700 

— 

240 

Mildewed  wheat  of  i805 

210 

178 

— 

32 

Blighted  wheat  of  1804 

650 

520 

— 

130 

Thick-skinned  Sicilian 

wheat  of  1810 

'iSS 

725 

» 

230 

Thin-skinned    Sicilian 

wheat  of  1810  - 

961 

722 

«. 

239 

Wheat  from  Poland      - 

950 

750 

— 

200 

North  American  wheat 

955 

730 

. 

225 

Norfolk  barley      - 

920 

790 

70 

60 

Oats  from  Scotland      « 

743 

641 

15 

87 

Rye  from  Yorkshire      - 

792 

645 

38 

109 

Common  bean 

570 

426 

_ 

103 

41 

Dry  peas     - 

574 

501 

22 

35 

16 

Potatoes       -         -              ^ 

from  260 

from  200 

from  20 

from  40 

to  200 

to  155 

to  15 

to  30 

Linseed  cake 

151 

123 

11 

1'. 

Red  beet 

148 

14 

121 

13 

'    White  beet 

136 

13 

119 

4 

Parsnip 

99 

9 

90 

Carrots 

98 

3 

95 

Common  turnips  - 

42 

7 

34 

1 

Swedish  turnips   . 

64 

9 

51 

2 

2 

Cabbage 

73 

41 

24 

3 

Broad-leaved  clover      - 

39 

31 

3 

2 

3 

Long-rooted  clover 

39 

SO 

4 

3 

2 

White  clover 

32 

29 

1 

3 

5 

Sainfoin 

39 

28 

2 

3 

6 

Lucerne 

23 

18 

1 

_ 

4 

Meadow  fox-tail  grass 

33 

24 

3 

^ 

6 

Perennial  rye  grass 

39 

26 

4 

_ 

5 

Fertile  meadow  grass   • 

78 

65 

6 

_ 

7 

Roughtsh  meadow  grass 

39 

29 

5 

__ 

6 

Crested  dog's-tail  grass 

35 

28 

3 

_ 

4 

Spiked  fescue  grass      - 

19 

15 

2 

^ 

2 

Sweet-scented  soft  grass 

82 

72 

4 

^ 

6 

Sweet-scented  vernal  grass 

50 

43 

4 

__ 

3 

Fiorin 

54 

46 

5 

I 

2 

Fiorin  cut  in  winter    - 

1       76 

64 

8 

1 

3 

C  134  3 

All  these  substances  were  submitted  to  experi- 
ment green,  and  in  their  natural  states.  It  is  probable 
that  the  excellence  of  the  different  articles  as  food 
will  be  found  to  be  in  a  great  measure  proportional  to 
the  quantities  of  soluble  or  nutritive  matters  they 
afford;  but  still  these  quantities  cannot  be  regarded  as 
absolutely  denoting  their  value.  Albuminous  or  glutin- 
ous matters  have  the  characters  of  animal  substances; 
sugar  is  more  nourishing,  and  extractive  matter  less 
nourishing,  than  any  other  principles  composed  of  car- 
bon, hydrogene,  and  oxygene.  Certain  combinations 
likewise  of  these  substances  may  be  more  nutritive 
than  others. 

I  have  been  informed  by  Sir  Joseph  Banks,  that 
the  Derbyshire  miners  in  winter,  prefer  oat  cakes  to 
wheaten  bread;  finding  that  this  kind  of  nourish- 
ment enables  them  to  support  their  strength  and  per- 
form their  labour  better.  In  summer,  they  say  oat 
cake  heats  them,  and  they  then  consume  the  finest 
wheaten  bread  they  can  procure.  Even  the  skin  of 
the  kernel  of  oats  probably  has  a  nourishing  power, 
?md  is  rendered  partly  soluble  in  the  stomach  with  the 
starch  and  gluten.  In  most  countries  of  Europe,  ex- 
cept Britain,  and  in  Arabia,  horses  are  fed  with  barley 
mixed  with  chopped  straw;  and  the  chopped  straw 
seems  to  act  the  same  part  as  the  husk  of  the  oat.  In 
the  mill  14lbs.  of  good  wheat  yield  on  an  average 
ISlbs.  of  flour,  the  same  quantity  of  barley  12lbs.  and 
of  oats  only  8lbs, 

In  the  south  of  Europe,  hard  or  thin-skinned 
wheat  is  in  higher  estimation,  than  soft  or  thick-skin- 


C  135         ] 

ned  wheat:  the  reason  of  which  is  obvious,  from  the 
larger  quantity  of  gluten  and  nutritive  matter  it  con- 
tains. I  have  made  an  analysis  of  only  one  specimen 
of  thin-skinned  wheat,  so  that  other  specimens  may 
possibly  contain  more  nutritive  matter  than  that  in  the 
Table:  the  Barbary  and  Sicilian  wheats,  before  refer- 
red to,  were  thick-skinned  wheats,  in  England  the  dif- 
ficulty of  grinding  thin-skinned  wheat  is  an  objection; 
but  this  difficulty  is  easily  overcome  by  moistening  the 
corn.* 


•  For  the  following  note  on  this  subject  I  am  indebted  to  the  kindness  of  the 
Right  Hon.  Sir  Joseph  Batiks,  Bart.  K.  B. 
Information  receivtd  from  John  yeffery,  Esq.  His  Majesty's  Consul  General  at  Lisbon, 

in  AnsiBer  to  Qxieriei  transmitted  to  him,  from  the  Comm.  of  P.  C.for  "Trade, 

dated  yan.  I2,l8l2. 

To  grind  hard  corn  with  the  ralll-stones  used  in  England,  the  wheat  must  be 
well  screened,  then  sprinkled  with  water  at  the  miller's  discretion,  andlaid  in  heaps 
and  frequently  turned  and  thoroughly  mixed,  which  will  soften  the  husk  so  as  to 
make  it  separate  from  the  flour  in  grinding,  and  of  course  give  the  flour  a  brighter 
colour;  otherwise  the  flinty  quality  of  the  wheat,  and  the  thinness  of  the  skin  will 
prevent  its  separation,  and  will  render  the  flour  unfit  for  making  into  bread. 

I  am  informed  by  a  miller  of  considerable  experience,  and  who  works  his  mills 
entirely  with  the  stones  from  England  or  Ireland,  that  he  frequently  prepares  the 
hard  Barbary  corn  by  immersing  it  in  water  in  close  wicker  baskets,  and  spreading 
it  thinly  on  a  floor  to  dry;  much  depends  on  the  judgment  and  skill  of  the  miller  ia. 
preparing  the  corn  for  the  mill  according  to  its  relative  quality,  I  beg  to  observe, 
that  it  is  not  from  this  previous  process  of  Wetting  the  corn  that  the  weight  in  th© 
flour  of  hard  corn  is  encreased;  bat  from  its  natural  quality  it  imbibes  considerably 
more  water  in  making  it  into  bread.  The  millstones  must  not  be  cut  too  deep,  but 
the  furrows  very  fine,  and  picked  in  the  usual  way.  The  mills  should  work  with  less 
velocity  in  grinding  hard  corn  than  with  soft,  and  set  to  work  at  first  with  soft 
corn,  till  the  mill  ceases  to  work  well;  then  put  on  the  hard  corn.  Hard  wheat  al- 
ways sells  at  a  higher  price  in  the  market  than  soft  wheat,  on  an  average  of  ten  to 
fifteen  per  cent;  as  it  produces  more  float  in  proportion,  and  less  bran  than  the 
soft  corn. 

Flour  made  from  hard  wheat  is  more  esteemed  than  what  is  made  froiji  soft 
cqfn  and  t>oth  sorts  are  applied  to  every  pnrpo^. 


136 


LECTURE  IV. 


On  Soils:  their  constituent  Parts.  On  the  analysis  of 
Soils.  Of  the  Uses  of  the  Soil  Of  the  Rocks  and 
Strata  found  beneath  Soils.  Of  the  improvemep 
of  Soil. 

No  subjects  are  of  more  importance  to  the  far- 
mer than  the  nature  and  improvement  of  soils;  and  no 
parts  of  the  doctrines  of  agriculture  are  more  capable 
of  being  illustrated  by  chemical  enquiries. 

Soils  are  extremely  diversified  in  appearance  and 
quality;  yet  as  it  was  stated  in  the  introductory  Lec- 
ture, they  consist  of  different  proportions  of  the  same 
elements;  which  are  in  various  states  of  chemical  com- 
bination, or  mechanical  mixture. 

The  substances  which  constitute  soils  have  been 
already  mentioned.  They  are  certain  compounds  of 
the  earths,  silica,  lime,  alumina,  magnesia,  and  of  the 
oxides  of  iron  and  manganesum;  animal  and  vegetable 
matters  in  a  decomposing  state,  and  saline,  acid  or  al- 
kaline combinations. 

In  all  chemical  experiments  on  the  composition 
of  soils  connected  with  agriculture,  the  constituent 


The  fiour  of  hard  wheat  is  in  general  superior  to  that  made  from  soft;  and 
there  is  no  difference  in  the  processof  making  them  into  bread;  but  the  flour  from 
hard  wheat  will  imbibe  and  retain  more  water  in  making  into  bread;  and  will  con- 
sequently produce  more  weight  of  bread:  it  is  the  practice  here,  and  which  I  am 
persuaded  it  would  be  adviseable  to  adopt  in  England,  to  make  bread  with  flour  of 
hard  and  soft  wheat,  which,  by  being  mixed,  will   make  the  bread    much  better. 

(Signed)  JOHN  JEFFERY. 


C         137         j 

parts  obtained  are  compounds;  and  they  act  as  com^- 
pounds  in  nature:  it  is  in  this  state,  therefore,  that  I 
shall  describe  their  characteristic  properties. 

1.  Silica^  or  the  earth  of  Jl'mts^  in  its  pure  and 
crystallized  form,  is  the  substance  known  by  the  name 
of  rock  crystal,  or  Cornish  diamond.  As  it  is  procur- 
ed by  chemists,  it  appears  in  the  form  of  a  white 
impalpable  powder.  .  It  is  not  soluble  in  the  common 
acids,  but  dissolves  by  heat  in  fixed  alkaline  lixivia. 
It  is  an  incombustible  substance,  for  it  is  saturated 
with  oxygene.  I  have  proved  it  to  be  a  compound  of 
oxygene,  and  the  peculiar  combustible  body  which  I 
have  named  silicum;  and  from  the  experiments  of  Ber- 
zelius,  it  is  probable  that  it  contains  nearly  equal 
weights  of  these  two  elements. 

2.  The  sensible  properties  of  lime  are  well 
known.  It  exists  in  soils  usually  united  to  carbonic 
acid;  which  is  easily  disengaged  from  it  by  the  attrac- 
tion of  the  common  acids.  It  is  sometimes  found 
combined  with  the  phosphoric  and  sulphuric  acids. 
Its  chemical  properties  and  agencies  in  its  pure  state 
will  be  described  in  the  Lecture  on  manures  obtained 
from  the  mineral  kingdom.  It  is  soluble  in  nitric  and 
muriatic  acids,  and  forms  a  substance  with  sulphuric 
acid,  difficult  of  solution,  called  gypsum.  It  is  not 
soluble  in  alkaline  solutions.  It  consists  of  one  pro- 
pordon  40  of  the  peculiar  metallic  substance,  which  I 
have  named  calcium;  and  one  proportion  15  of  oxy-* 
gene. 

3.  Alumina  exists  in  a  pure  and  crystallized  state 
in  the  white  sapphire,  and  united  to  a  little  oxide  of 

T 


[  138  ] 

iron  and  silica  in  the  other  oriental  gems.  In  the  state 
in  which  it  is  procured  by  chemists,  it  appears  as  a 
white  ppwder,  soluble  in  acids  and  fixed  alkaline  li- 
quors. From  my  experiments,  it  appears  that  alumi- 
na consists  of  one  proportion  33  of  aluminum,  and 
one  15  of  oxygene. 

4.  Magnesia  exists  in  a  pure  crystallized  state, 
constituting  a  mineral  like  talc  found  in  North  Ame- 
rica. In  its  common  form  it  is  the  magnesia  usta,  or 
calcined  magnesia  of  druggists.  It  generally  exists  in 
soils  combined  with  carbonic  acid.  It  is  soluble  in  all 
the  mineral  acids;  but  not  in  alkaline  lixivia.  It  is  dis- 
tinguished from  the  other  earths  found  in  soils  by  its 
ready  solubility  in  solutions  of  alkaline  carbonates, 
saturated  with  carbonic  acid.  It  appears  to  consist  of 
38  magnesmm  and  15  oxygene. 

5.  There  are  two  well  known  oxides  of  iron^  the 
black  and  the  brown.  The  black  is  the  substance  that 
flies  off  when  red  hot  iron  is  hammered.  The  brown 
oxide  may  be  formed  by  keeping  the  black  oxide  red 
hot,  for  a  long  time  in  contact  with  air.  The  first 
seems  to  consist  of  one  proportion  of  iron  103,  and 
two  of  oxygene  30;  and  the  second  of  one  proportion 
of  iron  103,  and  three  proportions  of  oxygene  45. 
The  oxides  of  iron  sometimes  exist  in  soils  combined 
with  carbonic  acid.  They  are  easily  distinguished  from 
other  substances  by  their  giving  when  dissolved  in 
acids  a  black  colour  to  solution  of  galls,  and  a  bright 
blue  precipitate  to  solution  of  prussiate  of  potassa  and 

iron. 

6.  The  oxide  of  manganeswn  is  the  substance  com- 
monly called  manganese,  and  used  in  bleeching.    It 


[         139        3 

appears  to  be  composed  of  one  proportion  of  mangan- 
esum  113,  and  three  of  oxygene  45.  It  is  distinguish- 
ed from  the  other  substances  found  in  soils,  by  its  pro- 
perty of  decomposing  muriatic  acid,  and  converting  it 
into  chlorine. 

1,  Vegetable  and  animal  matters  are  known  by  their 
sensible  qualities,  and  by  their  property  of  being  de- 
composed by  heat.  Their  characters  may  be  learnt 
from  the  details  in  the  last  Lecture. 

8.  The  saline  compounds  found  in  soils,  are  com- 
mon-salt, sulphate  of  magnesia,  sometimes  sulphate  of 
iron,  nitrates  of  lime  and  of  magnesia,  sulphate  of  po- 
tassa,  and  carbonates  of  potassa  and  soda.  To  des- 
cribe their  characters  minutely  will  be  unnecessary;  the 
tests,  for  most  of  them  have  been  noticed  p.  103. 

The  silica  in  soils  is  usually  combined  with  alumi- 
na and  oxide  of  iron,  or  with  alumina,  lime,  magnesia, 
and  oxide  of  iron,  forming  gravel  and  sand  of  differ- 
ent degrees  of  fineness.  The  carbonate  of  lime  is 
usually  in  an  impalpable  form,  but  sometimes  in  the 
state  of  calcareous  sand.  The  magnesia,  if  not  com- 
bined in  the  gravel  and  sand  of  soil,  is  in  a  fine  pow- 
der united  to  carbonic  acid.  The  impalpable  part  of 
the  soil,  which  is  usually  called  clay  or  loam,  consists 
of  silica,  alumina,  lime,  and  magnesia;  and  is^  in  fact, 
usually  of  the  same  composition  as  the  hard  sand,  but 
more  finely  divided.  The  vegetable  or  animal,  mat- 
ters, (and  the  first  is  by  far  the  most  common  in  soils) 
exist  in  different  states  of  decomposition.  They  are 
sometimes  fibrous,  sometimes  entirely  broken  down 
and  mixed  with  the  soil» 


£  140  ] 

To  form  a  just  idea  of  soils,  it  is  necessary  to 
conceive  different  rocks  decomposed,  or  ground  into 
parts  and  powder  of  different  degrees  of  fineness; 
some  of  their  soluble  parts  dissolved  by  water,  and 
that  water  adhering  to  the  mass,  and  the  whole  mixed 
with  larger  or  smaller  quantities  of  the  remains  of  ve- 
getables and  animals,  in  different  stages  of  decay. 

It  will  be  necessary  to  describe  the  processes  by 
which  all  the  varieties  of  soils  may  be  analysed.  I 
shall  be  minute  in  these  particulars,  and,  I  fear,  tedi- 
ous; but  the  philosophical  farmer  will,  I  trust,  feel  the 
propriety  of  full  details  on  this  subject. 

The  instruments  required  for  the  analysis  of  soils 
are  few,  and  but  little  expensive.  They  are  a  balance 
capable  of  containing  a  quarter  of  a  pound  of  com- 
mon soil,  and  capable  of  turning  when  loaded,  with 
a  grain;  a  set  of  weights  from  a  quarter  of  a  pound 
Troy  to  a  grain;  a  wire  sieve,  sufficiently  coarse  to  ad- 
mit a  mustard  seed  through  its  apertures;  an  Argand 
lamp  and  stand;  some  glass  bottles;  Hessian  crucible; 
porcelain,  or  queen's  ware  evaporating  basons;  a 
Wedgewood  pestle  and  mortar;  some  filtres  made  of 
half  a  sheet  of  blotting  paper,  folded  so  as  to  contain  a 
pint  of  liquid,  and  greased  at  the  edges;  a  bone  knife, 
and  an  apparatus  for  collecting  and  measuring  aeriform 
fluids. 

The  chemical  substances  or  reagents  required 
for  separating  the  constituent  parts  of  the  soil,  have, 
for  the  most  part,  been  mentioned  before:  they  are 
muriatic  acid  (spirit  of  salt) ^  sulphuric  acid,  pure  vola- 
tile alkali  dissolved  in  water,  solution  of  prussiate  of 


C      141      ] 

potash  and  iron,  succinate  of  ammonia,  soap  lye,  or 
solution  of  potossa,  solutions  of  carbonate  of  ammo- 
nia, of  muriate  of  ammonia,  of  neutral  carbonate  of 
potash,  and  nitrate  of  ammoniac. 

In  cases  when  the  general  nature  of  the  soil  of  a 
field  is  to  be  ascertained,  specimens  of  it  should  be 
taken  from  different  places,  two  or  three  inches  below 
the  surface,  and  examined  as  to  the  similarity  of  their 
properties.  It  sometimes  happens,  that  upon  plains 
the  whole  of  the  upper  stratum  of  the  land  is  of  the 
same  kind,  and  in  this  case,  one  analysis  will  be  suffi- 
cient ;  but  in  vallies,  and  near  the  beds  of  rivers,  there 
are  very  great  differences,  and  it  now  and  then  occurs 
that  one  part  ©fa  field  is  calcareous,  and  another 
part  siliceous  ;  and  in  this  case,  and  in  analogous  ca- 
ses, the  portions  different  from  each  other  should  be 
separately  submitted  to  experiment. 

Soils  when  collected,  if  they  cannot  be  imme- 
diately examined,  should  be  preserved  in  phials  quite 
filled  with  them,  and  closed  with  ground  glass  stop- 
pers. 

The  quantity  of  soil  most  convenient  for  a  perfect 
analysis,  is  from  two  to  four  hundred  grains.  It 
should  be  collected  in  dry  weather,  and  exposed  to 
the  atmosphere  till  it  becomes  dry  to  the  touch. 

The  specific  gravity  of  a  soil,  or  the  relation  of 
its  weight  to  that  of  water,  may  be  ascertained  by  in- 
troducing into  a  phial,  which  will  contain  a  known 
quantity  of  water,  equal  volumes  of  water  and  of  soil, 
and  this  may  be  easily  done  by  pouring  in  water  till  it 
IS  half  full,  and  then  adding  the  soil  till  the  fluid  rises 


C  142  3 

to  the  mouth  ;  the  difference  between  the  weight  of 
the  soil  and  that  of  the  water,  will  give  the  result. 
Thus  if  the  bottle  contains  four  hundred  grains  of 
water,  and  gains  two  hundred  grains  when  half  filled 
with  water  and  half  with  soil,  the  specific  gravity  of 
the  soil  will  be  2,  that  is,  it  will  be  twice  as  heavy  as 
water,  and  if  it  gained  one  hundred  and  sixty-five  grains, 
its  specific  gravity  would  be  1825,  water  being  1000. 

It  is  of  importance,  that  the  specific  gravity  of  a 
soil  should  be  known,  as  it  affords  an  indication  of 
the  quantity  of  animal  and  vegetable  matter  it  con- 
tains ;  these  substances  being  always  most  abundant 
in  the  lighter  soils. 

The  other  physical  properties  of  soils  should 
likewise  be  examined  before  the  analysis  is  made,  as 
they  denote,  to  a  certain  extent,  their  composition, 
and  serve  as  guides  in  directing  the  experiments. 
Thus  siHceous  soils  are  generally  rough  to  the  touch, 
and  scratch  glass  when  rubbed  upon  it ;  ferruginous 
soils  are  of  a  red  or  yellow  colour  j  and  calcareous 
soils  are  soft. 

1.  Soils,  though  as  dry  as  they  can  be  made  by 
continued  exposure  to  air,  in  all  cases  still  contain  a 
considerable  quantity  of  water,  which  adheres  with 
great  obstinacy  to  the  earths  and  animal  and  vegeta- 
ble matter,  and  can  only  be  driven  off  from  them  by 
a  considerable  degree  of  heat.  The  first  process  of 
analysis  is,  to  free  the  given  weight  of  soil  from  as 
much  of  this  water  as  possible,  without  in  other  res- 
pects, affecting  its  composition  ;  and  this  may  be  done 
by  heating  it  for  t^n  or  twelve  minutes  over  an  Ar- 


[  143  ]  '    ♦ 

gand*s  lamp,  in  a  bason  of  porcelain,  to  a  temperature 
equal  to  300  Fahrenheit ;  and  if  a  thermometer  is  not 
used,  the  proper  degree  may  be  easily  ascertained,  by 
keeping  a  piece  of  wood  in  contact  with  the  bottom  of 
the  dish  ;  as  long  as  the  colour  of  the  wood  remains 
unaltered,  the  heat  is  not  too  high  ;  but  when  the 
wood  begins  to  be  charred,  the  process  must  be  stop- 
ped. A  small  quantity  of  water  will  perhaps  remain 
in  the  soil  even  after  this  operation,  but  it  always  af- 
fords useful  comparative  results  ;  and  if  a  higher 
temperature  w^re  employed,  the  vegetable  or  animal 
matter  would  undergo  decomposition,  and  in  conse- 
quence the  experiment  be  wholly  unsatisfactory. 

The  loss  of  weight  in  the  process  should  be  care- 
fully noted,  and  when  in  four  hundred  grains  of  soil 
it  reaches  as  high  as  50,  the  soil  may  be  considered 
as  in  the  greatest  degree  absorbent,  and  retentive  of 
water,  and  will  generally  be  found  to  contain  much 
vegetable  or  animal  matter,  or  a  large  proportion  of 
aluminous  earth.  When  the  loss  is  only  from  20  to 
10,  the  land  may  be  considered  a&  only  slightly  absor- 
bent and  retentive,  and  siliceous  earth  probably  forms 
the  greatest  part  of  it. 

2.  None  of  the  loose  stones,  gravel,  or  large 
vegetable  fibres  should  be  divided  from  the  pure  soil 
till  after  the  water  is  drawn  off  j  for  these  bodies  are 
themselves  often  highly  absorbent  and  retentive,  and 
in  consequence  influence  the  fertility  of  the  land.  The 
next  process,  however,  after  that  of  heating,  should  be 
their  separation,  which  may  be  easily  accomplished  by 
the  sieve,  after  the  soil  has  been  gently  bruised  in  a 


[  144  } 

mortar.  The  weights  of  the  vegetable  fibres  or  wood, 
and  of  the  gravel  and  stones  should  be  separately 
noted  down,  and  the  nature  of  the  last  ascertained  ; 
if  calcereous,  they  will  effervesce  with  acids  ;  if  sili- 
ceous, they  will  be  sufficiently  hard  to  scratch  glass  ; 
and  if  of  the  common  alumihous  class  of  stones,  they 
will  be  soft,  easily  cut  with  a  knife,  and  incapable  of 
effervescing  with  acids. 

3.  The  greater  number  of  soils,  besides  gravel 
and  stones,  contain  larger  or  smaller  proportions  of 
sand  of  different  degrees  of  fineness ;  and  it  is  a  neces- 
sary operation,  the  next  in  the  process  of  analysis,  to 
detach  them  from  the  parts  in  a  state  of  more  minute 
division,  such  as  clay,  loam,  marie,  vegetable  and  ani- 
mal matter,  and  the  matter  soluble  in  water.  This 
may  be  effected  in  a  way  sufficiently  accurate,  by  boil- 
ing the  soil  in  three  or  four  times  its  weight  of  water  ; 
and  when  the  texture  of  the  soil  is  broken  down,  and 
the  water  cool ;  by  agitating  the  parts  together,  and 
then  suffering  them  to  rest.  In  this  case,  the  coarse 
sand  will  generally  separate  in  a  minute,  and  the  finer 
in  two  or  three  minutes,  whilst  the  highly  divided  earthy, 
animal,  or  vegetable  matter  will  remain  in  a  state  of  me- 
chanical supension  for  a  much  longer  time  ;  so  that  by 
pouring  the  water  from  the  bottom  of  the  vessel,  after 
one,  two  or  three  minutes,  the  sand  will  be  principally 
separated  from  the  other  substances,  which,  with  the 
water  containing  them,  must  be  poured  into  a  filtre, 
and  after  the  water  has  passed  through,  collected, 
dried,  and  weighed.  The  sand  must  likewise  be 
weighed,  and  the  respective  quantities  noted  down. 


[  145  ] 

The  water  of  lixiviation  must  be  preserved,  as  it  will 
be  found  to  contain  the  saline  and  soluble  animal  or 
vegetable  matters,  if  any  exist  in  the  soil. 

4.  By  the  process  of  washing  and  filtration,  the 
soil  is  separated  into  two  portions,  the  most  important 
of  which  is  generally  the  finely  divided  matter.  A 
minute  analysis  of  the  sand  is  seldom  or  never  neces- 
sary, and  its  nature  may  be  detected  in  the  same  man- 
ner as  that  of  the  stones  or  gravel.  It  is  always  either 
siliceous  sand,  or  calcareous  sand,  or  a  mixture  of 
both.  If  it  consist  wholly  of  carbonate  of  lime,  it  will 
be  rapidly  soluble  in  muriatic  acid,  with  effervescence ; 
but  if  it  consist  partly  of  this  substance,  and  partly  of 
siliceous  matter,  the  respective  quantities  may  be  as- 
certained by  weighing  the  residuum  after  the  action  of 
the  acid,  which  must  be  applied  till  the  mixture  has 
acquired  a  sour  taste,  and  has  ceased  to  effervesce. 
This  residuum  is  the  siliceous  part:  it  must  be  washed, 
dried,  and  heated  strongly  in  a  crucible;  the  difference 
between  the  weight  of  it  and  the  weight  of  the  whole, 
indicates  the  proportion  of  calcareous  sand. 

5.  The  finely  divided  matter  of  the  soil  is  usually 
very  compound  in  its  nature;  it  sometimes  contains  all 
the  f6ur  primitive  earths  of  soils,  as  well  as  animal  and 
vegetable  matter;  and  to  ascertain  the  proportions  of 
these  with  tolerable  accuracy,  is  the  most  difficult  part 
of  the  subject. 

The  first  process  to  be  performed,  in  this  part  of 
the  analysis,  is  the  exposure  of  the  fine  matter  of  the 
soil  to  the  action  of  muriatic  acid.  This  substance 
should  be  poured  upon  the  earthy  matter  in  an  eva- 

u 


C         146         ] 

porating  bason,  in  a  quantity  equal  to  twice  the  weight 
of  the  earthy  matter;  but  diluted  with  double  its  volume 
of  water.  The  mixture  should  be  often  stirred,  and 
suffered  to  remain  for  an  hour,  or  an  hour  and  a  half, 
before  it  is  examined. 

If  any  carbonate  of  lime  or  of  magnesia  exist  in 
the  soil,  they  will  have  been  dissolved  in  this  time  by 
the  acid,  which  sometimes  takes  up  likewise  a  little 
oxide  of  iron;  but  very  seldom  any  alumina. 

The  fluid  should  be  passed  through  a  filtre;  the 
solid  matter  collected,  washed  with  rain  water,  dried 
at  a  moderate  heat,  and  weighed.  Its  loss  will  denote 
the  quantity  of  solid  matter  taken  up.  The  washings 
must  be  added  to  the  solution,  which  if  not  sour  to  the 
taste,  must  be  made  so  by  the  addition  of  fresh  acid, 
when  a  little  solution  of  prussiate  of  potassa  and  iron 
must  be  mixed  with  the  whole.  If  a  blue  precipitate 
Occurs,  it  denotes  the  presence  of  oxide  of  iron,  and 
the  solution  of  the  prussiate  must  be  dropped  in  till 
no  farther  effect  is  produced.  To  ascertain  its  quan- 
tity, it  must  be  collected  in  the  same  manner  as  other 
solid  precipitates,  and  heated  red;  the  result  is  oxide 
of  iron,  which  may  be  mixed  with  a  little  oxide  of 
manganesum. 

Into  the  fluid  freed  from  oxide  of  iron,  a  solu- 
tion of  neutralized  carbonate  of  potash  must  be  pour- 
ed till  all  effervescence  ceases  in  it,  and  till  its  taste  and 
smell  indicate  a  considerable  excess  of  alkaline  salt. 

The  precipitate  that  falls  down  is  carbonate  of 
lime;  it  must  be  collected  on  the  filtre,  and  dried  at  a 
heat  below  that  of  redness. 


Xi 


L      147      3 

The  remaining  fluid  must  be  boiled  for  a  quarter 
of  an  hour,  when  the  magnesia,  if  any  exist,  will  be 
precipitated  from  it,  combined  with  carbonic  acid,  and 
its  quantity  is  to  be  ascertained  in  the  same  manner  as 
that  of  the  carbonate  of  lime. 

If  any  minute  proportion  of,  alumina  should, 
from  peculiar  circumstances,  be  dissolved  by  the  acid, 
it  will  be  found  in  the  precipitate  with  the  carbonate  of 
lime,  and  it  may  be  separated  from  it  by  boiling  it  for 
a  few  minutes  with  soap  lye,  sufficient  to  cover  the 
solid  matter;  this  substance  dissolves  alumina,  with- 
out acting  upon  carbonate  of  lime. 

Should  the  finely  divided  soil  be  sufficiently  cal- 
careous to  effervesce  very  strongly  with  acids,  a  very 
simple  method  may  be  adopted  for  ascertaining  the 
quantity  of  carbonate  of  lime,  and  one  sufficiently  ac- 
curate in  all  common  cases. 

Carbonate  of  lime,  in  all  its  states,  contains  a  de- 
terminate proportion  of  carbonic  acid,  i,  e,  nearly  43 
per  cent,  so  that  when  the  quantity  of  this  elastic  fluid 
giv^n  out  by  any  soil  during  the  solution  of  its  calcare- 
ous matter  in  an  acid  is  known,  either  in  weight  or 
measure,  the  quantity  of  carbonate  of  lime  may  be 
easily  discovered. 

When  the  process  by  diminution  of  weight  is 
employed,  two  parts  of  the  acid  and  one  part  of  the 
matter  of  the  soil  must  be  weighed  in  two  separate  bot- 
ties,  and  very  slowly  mixed  together  till  the  efferves- 
cence ceases;  the  difference  between  their  weight  be- 
fore and  after  the  experiment,  denotes  the  quantity 
of  carbonic  carbonic  acid  lostj  for  every  four  grains 


C  148  ] 

and  a  quarter  of  which,  ten  grains  of  carbonate  of 
lime  must  be  estimated. 

The  best  method  of  collecting  the  carbonic  acid, 
so  as  to  discover  its  volume,  is  by  a  peculiar  pneumat- 
ic, apparatus  *  in  which  its  bulk  may  be  measured  by 
the  quantity  of  water  it  dissolves. 

6.  After  the  calcareous  parts  of  the  soil  has  been 
acted  upon  by  muriatic  acid,  the  next  process  is  to  as- 
certain the  quantity  of  finely  divided  insoluble  animal 
and  vegetable  matter  that  it  contains. 

This  may  be  done  with  sufficient  precision,  by 
strongly  igniting  it  in  a  crucible  over  a  common  fire 
till  no  blackness  remains  in  the  mass.  It  should  be 
often  stirred  with  a  metallic  rod,  so  as  to  expose  new 
surfaces  continually  to  the  air;  the  loss  of  weight  that 
it  undergoes  denotes  the  quantity  of  the  substance 
that  it  contains  destructible  by  fire  and  aif". 

It  is  not  possible,  without  very  refined  and  diffi- 
cult experiments,  to  ascertain  whether  this  substance 


•Fig.  15.  A,  B,  C,  D,  represent  the  different  parts  of  this  apparatus.  A.  Repre- 
sents the  bottlefor  receiving  the  soil.  B.  the  bottle  containing  the  acid,  furnished 
•with  a  stop-cock.  C.  the  tube  connected  with  a  flaccid  bladder.  D.  The  graduated 
m»asure.  E.  The  bottle  for  containing  the  bladder.  When  this  instrument  is  used 
»  given  quantity  of  soil  is  introduced  into  A.  B  is  filled  with  muriatic  acid  diluted, 
■with  an  equal  quantity  of  water;  and  the  stop-cock  being  closed,  is  connected  with 
the  upper  orifice  of  A,  which  is  ground  to  receive  it.  The  tube  D  is  introduced 
into  the  lower  orifice  of  A,  and  the  bladder  connected  with  it  placed  in  its  flaccid 
state  into  E,  which  is  filled  with  water.  The  graduated  measure  is  placed  under  the 
tube  of  E.  When  the  stop-cock  of  B  is  turned,  the  acid  flows  into  A,  and  acts 
upon  the  soil;  the  elastic  fluid  generated  passes  through  C  into  the  bladder,  and 
displaces  a  quantity  of  water  in  E,  equal  to  it  in  bulk,  and  this  water  flows  through 
the  tube  into  the  graduated  measure:  and  gives  by  its  volume  the  indication  of 
the  proportion  of  carbonic  acid  disengaged  from  the  soil;  for  every  ounce  measure 
of  which  two  grains  of  carbonate  of  lime  may  be  estimated. 


P.148 


[  149  ] 

IS  wholly  animal  or  vegetable  matter,  or  a  mixture  of 
both.  When  the  smell  emitted  during  the  incinera- 
tion is  similar  to  that  of  burnt  feathers,  it  is  a  certain 
indication  of  some  substance  either  animal  or  analo- 
gous to  animal  matter ;  and  a  copious  blue  flame  at 
the  time  of  ignition,  almost  always  denotes  a  consi- 
derable proportion  of  vegetable  matter.  In  cases 
when  it  is  necessary  that  the  experiment  should  be 
very  quickly  performed,  the  destruction  of  the  decom- 
posable substances  may  be  assisted  by  the  agency  of 
nitrate  of  ammoniac,  which  at  the  time  of  ignition  may 
be  thrown  gradually  upon  the  heated  mass  in  the 
quantity  of  twenty  grains  for  every  hundred  of  residual 
soil.  It  accelerates  the  dissipation  of  the  animal  and 
vegetable  matter,  which  it  causes  to  be  converted  into 
elastic  fluids  ;  and  it  is  itself  at  the  same  time  decom- 
posed and  lost. 

7.  The  substances  remaining  after  the  destruc- 
tion of  the  vegetable  and  animal  matter,  are  generally 
minute  particles  of  earthy  matter,  containing  usually 
alumina  and  silica,  with  combined  oxide  of  iron  or 
of  manganesum. 

To  separate  these  from  each  other,  the  solid  mat- 
ter should  be  boiled  for  two  or  three  hours  with  sul- 
phuric acid,  diluted  with  four  times  its  weight  of  wa- 
ter ;  the  quantity  of  the  acid  should  be  regulated  by 
the  quantity  of  solid  residuum  to  be  acted  on,  allow- 
ing for  every  hundred  grains,  two  drachms  or  one 
hundred  and  twenty  grains  of  acid. 

The  substance  remaining  after  the  action  of  the 
acid,  may  be  considered  as  siliceous  j  and  it  must  be 


I         150        2 

separated  ancl  its  weight  ascertained,  after  washing, 
and  drying  in  the  usual  manner. 

The  alumina  and  the  oxide  of  iron  and  mangane- 
sum  if  any  exist,  are  all  dissolved  by  the  sulphuric  acid  ; 
they  may  be  separated  by  succinate  of  ammonia,  ad- 
ded to  excess  :  which  throws  down  the  oxide  of  iron, 
and  by  soap  lye,  which  will  dissolve  the  alumina,  but 
not  the  oxide  of  manganesum  ;  the  weights  of  the 
oxides  ascertained  after  they  have  been  heated  to  red- 
ness will  denote  their  quantities. 

Should  any  magnesia  and  lime  have  escaped  so- 
lution in  the  muriatic  acid,  they  will  be  found  in  the 
sulphuric  aqid  ;  this,  however,  is  rarely  the  case  ;  but 
the  process  for  detecting  them,  and  ascertaining  their 
quantities,  is  the  same  in  both  instances. 

The  method  of  analysis  by  sulphuric  acid,  is  suf- 
ficiently precise  for  all  usual  experiments  ;  but  if  very 
great  accuracy  be  an  object,  dry  carbonate  of  potassa 
must  be  employed  as  the  agent,  and  the  residuum  of 
the  incineration  (6)  must  be  heated  red  for  a  half  hour, 
with  four  times  its  weight  of  this  substance,  in  a  cruci- 
ble of  silver,  or  of  well  baked  porcelain.  The  mass 
obtained  must  be  dissolved  in  muriatic  acid,  and  the 
solution  evaporated  till  it  is  nearly  solid  j  distilled 
water  must  then  be  added,  by  which  the  oxide  of  iron 
and  all  the  earths,  except  silica,  will  be  dissolved  in 
combination  as  muriates.  The  silica,  after  the  usual 
process  of  lixiviation,  must  be  heated  red  j  the  other 
substances  may  be  separated  in  the  same  manner  as 
from  the  muriatic  and  sulphuric  solutions. 


[1^1     i    ^ 

This  process  is  the  one  usually  employed  by 
chemical  philosophers  for  the  analysis  of  stones, 

S.  If  any  saline  matter,  or  soluble  vegetable  or 
animal  matter  is  suspected  in  the  soil,  it  will  be  found 
in  the  water  of  lixiviation  used  for  separating  the 
sand. 

This  water  must  be  evaporated  to  dryness  in  a- 
proper  dish,  at  a  heat  below  its  boiling  point. 

If  the  solid  matter  obtained  is  of  a  brown  colour 
and  inflammable,  it  may  be  considered  as  partly  vege- 
table extract.  If  its  smell,  when  exposed  to  heat,  be 
like  that  of  burnt  feathers,  it  contains  animal  or  albu- 
minous matter ;  if  it  be  white,  crystalline,  and  not 
destructible  by  heat,  it  may  be  considered  as  principal- 
ly saline  matter  ;  the  nature  of  which  may  be  known 
by  the  tests  described  page  103. 

9.  Should  sulphate  or  phosphate  of  lime  be  sus- 
pected in  the  entire  soil,  the  detection  of  them  re- 
quires a  particular  process  upon  it.  A  given  weight 
of  it,  for  instance  four  hundred  grains,  must  be  heat- 
ed red  for  half  an  hour  in  a  crucible,  mixed  with  one- 
third  of  powdered  charcoal.  The  mixture  must  be 
boiled  for  a  quarter  of  an  hour,  in  half  a  pint  of  water, 
and  the  fluid  collected  through  the  filtre,  and  exposed 
for  some  days  to  the  atmosphere  in  an  open  vessel. 
If  any  notable  quantity  of  sulphate  of  lime  (gypsum) 
existed  in  the  soil,  a  white  precipitate  will  gradually 
form  in  the  fluid,  and  the  weight  of  it  will  indicate  the 
proportion. 

Phosphate  of  lime,  if  any  exist,  may  be  separated 
from  the  soil  after  the  process  for  gypsum.     Muriatic^ 


C  152         ] 

acid  must  be  digested  upon  the  soil,  in  quantity  more 
than  sufficient  to  saturate  the  soluble  earths  ;  the 
solution  must  be  evaporated,  and  water  poured  upon 
the  solid  matter.  This  fluid  will  dissolve  the  com- 
pounds of  earths  with  the  muriatic  acid,  and  leave  the 
phosphate  of  hme  untouched. 

It  would  not  fall  within  the  limits  assigned  to  this 
Lecture,  to  detail  any  processes  for  the  detection  of 
substances  which  may  be  accidentally  mixed  with  the 
matters  of  soils.  Other  earths  and  metallic  oxides 
are  now  and  then  found  in  them,  but  in  quantities 
too  minute  to  bear  any  relation  to  fertility  or  barren- 
ness, and  the  search  for  them  would  make  analysis 
much  more  complicated  without  rendering  it  more 
useful. 

10.  When  the  examination  of  a  soil  is  comple- 
ted, the  products  should  be  numerically  arranged, 
and  theii'  quantities  added  together,  and  if  they  nearly 
equal  the  original  quantity  of  soil,  the  analysis  may  be 
considered  as  accurate.  It  must,  however,  be  noticed, 
that  when  phosphate  or  sulphate  of  lime  are  disco- 
vered by  the  independent  process  just  described,  (9,) 
a  correction  must  be  made  for  the  general  process,  by 
subtracting  a  sum  equal  to  their  weight  from  the 
quantity  of  carbonate  of  lime,  obtained  by  precipita- 
tion from  the  muriatic  acid. 

In  arranging  the  products,  the  form  should  be  in 
the  order  of  the  experiments  by  which  they  were  pro- 
cured. 

Thus,  I  obtained  from  400  grains  of  a  good  sili- 
ceous sandy  soil  from  a  hop  garden  near  Tunbridge, 
Kent,  ^         \ 


153 


grains 

Of  water  of  absorption 

- 

•• 

19 

Of  loose  stones  and  gravel  principally  siliceous  53 

Of  undecompounded  vegetable 

fibres 

- 

14 

Of  fine  siliceous  sand 

- 

- 

212 

Of  minutely  divided  matter  separated  by  : 

agitation    . 

and  filtration,  and  consisting  of 

Carbonate  of  lime 

- 

19 

Carbonate  of  magnesia 

m 

3 

Matter  destructible  by  heat,  principally 

vegetable        -         -         - 

- 

15 

Silica         -         -         .         . 

- 

21 

Alumina    -         -        - ,       - 

- 

IS 

Oxide  of  iron     - 

- 

5 

Soluble  matter,  principally  common 

salt  and  vegetable  extract 

- 

3 

Gypsum     .        -        -        « 

- 

2 

—         81 

Amount  of  all  the  products  379 
Loss  -  -  -  -  21 
The  loss  in  this  analysis  is  not  more  than  usually 
occurs,  and  it  depends  upon  the  impossibiHty  of  collec- 
ting the  whole  quantities  of  the  different  precipitates ; 
and  upon  the  presence  of  more  moisture  than  is  ac 
counted  for  in  the  water  of  absorption,  and  which  is  lost 
in  the  different  processes. 

When  the  experimenter  is  become  acquainted 
with  the  use  of  the  different  instruments,  the  proper- 
ties of  the  reagents,  and  the  relations  between  the  ex- 
ternal and  chemical  qualities  of  soils,  he  will  seldom 
find  it  necessary  to  perform,  in  any  one  case,  all  the 

X 


C  154  3 

processes  that  have  been  described.  When  his  soil, 
for  instance,  contains  no  notable  proportion  of  cal- 
careous matter,  the  action  of  the  muriatic  acid  (7) 
may  be  omitted.  In  examining  peat  soils,  he  will 
principally  have  to  attend  to  the  operation  by  fire 
and  air  (8)  ;  and  in  the  analysis  of  chalks  and  loams, 
he  will  often  be  able  to  omit  the  experiment  by  sul- 
phuric acid  (9). 

In  the  first  trials  that  are  made  by  persons  unac- 
quainted with  chemistry,  they  must  not  expect  much 
precision  of  result.  Many  difficulties  will  be  met 
with  :  but  in  overcoming  them,  the  most  useful  kind 
of  practical  knowledge  will  be  obtained  ;  and  nothing 
is  so  instructive  in  experimental  science,  as  the  detec- 
tion of  mistakes.  The  correct  analyst  ought  to  be  well 
grounded  in  general  chemical  information;  but  perhaps 
there  is  no  better  mode  of  gaining  it,  than  that  of  at- 
tempting original  investigations.  In  pursuing  his  expe- 
riments,  he  will  be  continually  obliged  to  learn  the  pro- 
perties of  the  substances  he  is  employing  or  acting 
upon  y  and  his  theoretical  ideas  will  be  more  valuable 
in  being  connected  with  practical  operations,  and  ac- 
quired for  the  purpose  of  discovery. 

Plants  being  possessed  of  no  locomotive  powers, 
can  grow  only  in  places  where  they  are  supplied  with 
food ;  and  the  soil  is  necessary  to  their  existence, 
both  as  affording  them  nourishment,  and  enabling 
them  to  fix  themselves  in  such  a  manner  as  to  obey 
those  mechanical  liaws  by  which  their  radicles  are  kept 
below  the  surface,  and  their  leaves  exposed  to  the  free 
atmosphere.     As  the  systems  of  roots,  branches,  and 


[155         ] 

leaves  are  very  dilFerent  in  different  vegetables,  so  they 
flourish  most  in  different  soils  :  the  plants  that  have 
bulbous  roots  require  a  looser  and  a  lighter  soil  than 
such  as  have  fibrous  roots  ;  and  the  plants  possessing 
only  short  fibrous  radicles  demand  a  firmer  soil  than 
such  as  have  tap  roots,  or  extensive  lateral  roots. 

A  good  turnip  soil  from  Holkham,  Norfolk,  af- 
forded me  8  parts  out  of  9  siliceous  sand  j  and  the 
finely  divided  matter  consisted 

Of  carbonate  of  lime     ^         ^  .  63 

-—  silica      -         -         -         -  -  15 

—  alumina  -        -        -  -  II 

—  oxide  of  iron  -         -         -  -  3         ^ 

—  vegetable  and  saline  matter  -  5 

—  moisture  -         -         -  -  3 

I  found  the  soil  taken  from  a  field  at  ShefBeld- 
place  in  Sussex,  remarkable  for  producing  flourishing 
oaks,  to  consist  of  six  parts  of  sand,  and  one  part 
of  clay  and  finely  divided  matter.  And  one  hundred 
parts  of  the  entire  soil  submitted  to  analysis  produced 


Silica           -        -        .        .        . 

parts, 
54 

Alumina      -        -        .        -        . 

28 

Carbonate  of  lime         .        -        . 

3 

Oxide  of  iron       .        .        .        « 

5 

Decomposing  vegetable  matter 

4 

Moisture  and  loss 

3 

An  excellent  wheat  soil  from  the  neighbourhood 

of  West  Drayton,.  Middlesex,  gave  3  parts 

in  5  of  sill- 

[  156  3 

ceous  sand;  and   the  finely  divided  matter  consis- 
ted of 

Carbonate  of  lime         -        -        -        28 

Silica 32 

Alumina      -         -         -         -         -         29 
Animal  or  vegetable  matter  and  moisture  1 1 

Of  these  soils  the  last  was  by  far  the  most,  and 
the  first  the  least,  coherent  in  texture.     In  all  cases 
the  constituent  parts  of  the  soil  which  give  tenacity  and 
coherence  are  the  finely  divided  matters  ;  and  they 
possess  the  power  of  giving  those  qualities  in   the 
highest  degree  when  they  contain  much  alumina.     A 
small  quantity  of  finely  divided  matter  is  sufficient  to 
fit  a  soil  for  the  production  of  turnips  and  barley ;  and 
I  have  seen  a  tolerable  crop  of  turnips  on  a  soil  con- 
taining 1 1  parts  out  of  1 2  sand.    A  much  greater  pro- 
portion of  sand,  however,  always   produces  absolute 
sterility.     The  soil  of  Bagshot  heath,  which  is  entire- 
ly devoid  of  vegetable  covering,  contains  less  than  /^j 
of  finely  divided  matter.     400  parts  of  it,  which  had 
been  heated  red,  afforded  me  580  parts  of  coarse  sili- 
ceous sand  ;  9  parts  of  fine  siliceous  sand,  and  1 1 
parts  of  impalpable  matter  which  was  a  mixture  of  fer- 
ruginous clay,  with  carbonate  of  lime.     Vegetable  or 
animal  matters,  when  finely  divided,  not  only  give  co- 
herence, but  likewise  softness  and  penetrability ;  but 
neither  they  nor  any  other  part  of  the  soil  must  be  in 
too  great  proportion  ;  and  a  soil  is  unproductive  if  it 
consist  entirely  of  impalpable  matters. 

Pure  alumina  or  silica,  pure  carbonate  of  lime, 
or  carbonate  of  magnesia,  are  incapable  of  supporting 
healthy  vegetation. 


C  157  ] 

No  soil  is  fertile  that  contains  as  much  as  19  parts 
out  of  20  of  any  of  the  constituents  that  have  been 
mentioned. 

It  will  be  asked,  are  the  pure  earths  in  the  soil 
merely  active  as  mechanical  or  indirect  chemical 
agents,  or  do  they  actually  afford  food  to  the  plant? 
This  is  an  important  question;  and  not  difficult  of  sol- 
ution. 

The  earths  consist,  as  I  have  before  stated,  of 
metals  united  to  oxygene;  and  these  metals  have  not 
been  decomposed;  there  is  consequently  no  reason  to 
suppose  that  the  earths  are  convertible  into  the  ele- 
ments of  organized  compounds,  into  carbon,  hydro- 
gene,  and  azote. 

Plants  have  been  made  to  grow  in  given  quanti- 
ties of  earth.  They  consume  very  small  portions  only; 
and  what  is  lost  may  be  accounted  for  by  the  quantities 
found  in  their  ashes;  that  is  to  say,  it  has  not  been 
converted  into  any  new  products. 

The  carbonic  acid  united  to  lime  or  magnesia,  if 
any  stronger  acid  happens  to  be  formed  in  the  soil 
during  the  fermentation  of  vegetable  matter  which  will 
disengage  it  from  the  earths,  may  be  decomposed: 
but  the  earths  themselves  cannot  be  supposed  convert- 
ible into  other  substances,  by  any  process  taking  place 
in  the  soil. 

In  all  cases  the  ashes  of  plants  contain  some  of 
the  earths  of  the  soil  in  which  they  grow;  but  these 
earths,  as  may  be  seen  from  the  table  of  the  ashes  af- 
forded by  different  plants  given  in  the  last  Lecture, 
never  equal  more  than  to  of  the  weight  of  the  plant 
consumed. 


[158         J 

If  they  be  considered  as  necessary  to  the  vegeta- 
ble, it  is  as  giving  hardness  and  firmness  to  its  organi- 
zation. Thus,  it  has  been  mentioned  that  wheat,  oats, 
and  many  of  the  hollow  grasses,  have  an  epidermis 
principally  of  siliceous  earth;  the  use  of  which  seems 
to  be  to  strengthen  them,  and  defend  them  from  the 
attacks  of  insects  and  parasitical  plants. 

Many  soils  are  popularly  distinguished  as  cold; 
and  the  distinction,  though  at  first  view  it  may  appear 
to  be  founded  on  prejudice,  is  really  just. 

Some  soils  are  much  more  heated  by  the  rays  of 
the  sun,  all  other  circumstances  being  equal,  than 
others;  and  soils  brought  to  the  same  degree  of  heat 
cool  in  different  times,  /.  e,  some  cool  much  faster 
than  others. 

This  property  has  been  very  little  attended  to  in 
a  philosophical  point  of  view;  yet  it  is  of  the  highest 
importance  in  agriculture.  In  general,  soils  that  con- 
sist principally  of  a  stiff  white  clay  are  difficultly  heated; 
and  being  usually  very  moist,  they  retain  their  heat 
only  for  a  short  time.  Chalks  are  similar  in  one  res- 
pect, that  they  are  difficultly  heated;  but  being  drier 
they  retain  their  heat  longer,  less  being  consumed  in , 
causing  the  evaporation  of  their  moisture. 

A  black  soil,  containing  much  soft  vegetable  mat- 
ter, is  most  heated  by  the  sun  and  air;  and  the  col- 
oured soils,  and  the  soils  containing  much  carbonace- 
ous matter,  or  ferruginous  matter,  exposed  under 
equal  circumstances  to  sun,  acquire  a  much  higher 
temperature  than  pale-coloured  soils. 


C  159         3 

When  soils  are  perfectly  dry,  those  that  most 
readily  beceme  heated  by  the  solar  rays  likewise  cool 
most  rapidly;  but  I  have  ascertained  by  experiment,  that 
the  darkest  coloured  dry  soil  (that  which  contains 
abundance  of  animal  or  vegetable  matter;  substances 
which  most  facilitate  the  diminution  of  temperature,) 
when  heated  to  the  same  degree,  provided  it  be  with- 
in the  common  limits  of  the  effect  of  solar  heat,  \yill 
cool  more  slowly  than  a  wet  pale  soil,  entirely  cotn- 
posed  of  earthy  matter. 

I  found  that  a  rich  black  mould,  which  contained 
nearly  i  of  vegetable  matter,  had  its  temperature  in- 
creased in  an  hour  from  65^  to  88°  by  exposure  to 
sunshine;  whilst  a  chalk  soil  was  heated  only  to  69° 
under  the  same  circumstances.  But  the  mould  re- 
moved into  the  shade,  where  the  temperature  was  62°, 
lost,  in  half  an  hour,  15°;  whereas  the  chalk,  under 
the  same  circumstances,  had  lost  only  4°. 

A  brown  fertile  soil,  and  a  cold  barren  clay  were 
each  artificially  heated  to  88°^  having  been  previously 
dried:  they  were  then  exposed  to  a  temperature  of  57°; 
in  half  an  hour  the  dark  soil  was  found  to  have  lost  9° 
of  heat;  the  clay  had  lost  only  6°.  An  equal  portion 
of  the  clay  containing  moisture,  after  being  heated  to 
88°,  was  exposed  in  a  temperature  of  5 5"^;  in  less  than 
a  quarter  of  an  hour  it  was  found  to  have  gained  the 
temperature  of  the  room.  The  soils  in  all  these  ex- 
periments were  placed  in  small  tin  plate  trays  two 
inches  square,  and  half  an  inch  in  depth;  and  the  tem- 
perature ascertained  by  a  delicate  thermometer. 

Nothing  can  be  more  evident,  than  that  the 


C         160         ] 

genial  heat  of  the  soil,  particularly  in  spring,  must  be 
of  the  highest  importance  to  the  rising  plant.  And 
when  the  leaves  are  fully  developed,  the  ground  is 
shaded;  and  any  injurious  influence,  which  in  the  sum- 
mer might  be  expected  from  too  great  a  heat,  entirely 
prevented:  so  that  the  temperature  of  the  surface, 
when  bare  and  exposed  to  the  rays  of  the  sun,  affords 
at  least  one  indication  of  the  degrees  of  its  fertility;  and 
the  thermometer  may  be  sometimes  a  useful  instru- 
ment to  the  purchaser  or  improver  of  lands. 

The  moisture  in  the  soil  influences  its  tempera- 
ture; and  the  manner  in  which  it  is  distributed  through, 
or  combined  with,  the  earthy  materials,  is  of  great 
importance  in  relation  to  the  nutriment  of  the  plant. 
If  water  is  too  strongly  attracted  by  the  earths,  it  will 
not  be  absorbed  by  the  roots  of  the  plants;  if  it  is  in 
too  great  quantity,  or  too  loosely  united  to  them,  it 
tends  to  injure  or  destroy  the  fibrous  parts  of  the 
roots. 

There  are  two  states  in  which  water  seems  to 
exist  in  the  earths,  and  in  animal  and  vegetable  substan- 
ces: in  the  first  state  it  is  united  by  chemical,  in  the 
other  by  cohesive  attraction. 

If  pure  solution  of  ammonia  or  potassa  be  poured 
into  a  solution  of  alum,  alumina  falls  down  combined 
widi  water;  and  the  water  dried  by  exposure  to  air  will 
aflbrd  more  than  half  its  weight  of  water  by  distilla- 
tion; in  this  instance  the  water  is  united  by  chemical 
attraction.  The  moisture  which  wood,  or  muscular 
fibre,  or  gum,  that  have  been  heated  to  212°,  afford 
by  distillation  at  a  red  heat,  is  likewise  water,  the  ele- 


C      161       3 

ments  of  which  were  united  in  the  substance  by  che- 
mical combination. 

When  pipe-clay  dried  at  the  temperature  of  the 
atmosphere  is  brought  in  contact  with  water,  the  fluid 
is  rapidly  absorbed  ;  this  is  owing  to  cohesive  attrac- 
tion. Soils  in  general,  vegetable,  and  animal  sub- 
stances, that  have  been  dried  at  a  heat  below  that  of 
boiling  water,  increase  in  weight  by  exposure  to  air, 
owing  to  their  absorbing  water  existing  in  the  state  of 
vapour  in  the  air,  in  consequence  of  cohesive  attrac- 
tion. 

The  water  chemically  combined  amongst  the  ele- 
ments of  soils,  unless  in  the  case  of  the  decomposition 
of  animal  or  vegetable  substances,  cannot  be  absorbed 
by  the  roots  of  plants  ;  but  that  adhering  to  the  parts 
of  the  soil  is  in  constant  use  in  vegetation.  Indeed 
there  are  few  mixtures  of  the  earths  found  in  soils, 
that  contain  any  chemically  combined  water ;  water 
is  expelled  from  the  earths  by  most  substances  that 
combine  with  them.  Thus,  if  a  combination  of  lime 
and  water  be  exposed  to  carbonic  acid,  the  carbonic 
acid  takes  the  place  of  water  ;  and  compounds  of  alu- 
mina and  silica,  or  other  compounds  of  the  earths,  do 
not  chemically  unite  with  w^ater:  and  soils,  as  it  has 
been  stated,  are  formed  either  by  earthy  carbonates, 
or  compounds  of  the  pure  earths  and  metallic  oxides. 

When  saline  substances  exist  in  soils,  they  may 
be  united  to  water  both  chemically  and  mechanically  j 
but  they  are  always  in  too  small  a  quantity  to  influence 
materially  the  relations  of  the  soil  to  water. 


t         162         J 

The  power  of  the  soil  to  absorb  water  by  cohe- 
sive attraction,  depends  in  great  measure  upon  the 
state  of  division  of  its  parts  ;  the  more  divided  they 
are,  the  greater  is  their  absorbent  power.  The  differ- 
ent constituent  parts  of  soils  likewise  appear  to  act, 
even  by  cohesive  attraction,  with  different  degrees  of 
energy.  Thus  vegetable  substances  seem  to  be  more 
absorbent  than  animal  substances  ;  animal  substances 
more  so  than  compounds  of  alumina  and  silica ;  and 
compounds  of  alumina  and  silica  more  absorbent  than 
corbonates  of  lime  and  magnesia :  these  differences 
may,  however,  possibly  depend  upon  the  differences 
in  their  state  of  division,  and  upon  the  surface  ex- 
posed. 

The  power  of  soils  to  absorb  water  from  air,  is 
much  connected  with  fertility.  When  this  power  is 
great,  the  plant  is  supplied  with  moisture  in  dry  sea- 
sons ;  and  the  effect  of  evaporation  in  the  day  is  coun- 
teracted by  the  absorption  of  aqueous  vapour  from 
the  atmosphere,  by  the  interior  parts  of  the  soil  during 
the  day,  and  by  both  the  exterior  and  interior  during 
night. 

The  stiff  clays  approaching  to  pipe- clays  in  their 
nature,  which  take  up  the  greatest  quantity  of  water 
when  it  is  poured  upon  them  in  a  fluid  form,  are  not 
the  soils  which  absorb  most  moisture  from  the  atmos- 
phere in  dry  weather.  They  cake,  and  present  only  a 
small  surface  to  the  air ;  and  the  vegetation  on  them 
IS  generally  burnt  up  almost  as  readily  as  on  sands. 

The  soils  that  are  most  efficient  in  supplying  the 
plant  with  water  by  atmospheric  absorption,  are  those 


[  163  '       3 

in  which  there  Is  a  due  mixture  of  sand,  finely  divided 
clay,  and  carbonate  of  lime,  with  some  animal  or  ve- 
getable matter  ;  and  which  are  so  loose  and  light  as 
to  be  freely  permeable  to  the  atmosphere.  With  res- 
pect to  this  quality,  carbonate  of  lime  and  animal  and 
vegetable  matter  are  of  great  use  in  soils  ;  they  give 
absorbent  power  to  the  soil  without  giving  it  likewise 
tenacity  :  sand,  which  also  destroys  tenacity,  on  the 
contrary,  gives  little  absorbent  power. 

I  have  compared  the  absorbent  po^yers  of  many 
soils  with  respect  to  atmospheric  moisture,  and  I  have 
always  found  it  greatest  in  the  most  fertile  soils  :  so 
that  it  affords  one  method  of  judging  of  the  produc- 
tiveness of  land. 

1000  parts  of  a  celebrated  soil  from  Ormiston, 
in  East  Lothian,  which  contained  more  than  half  its 
weight  of  finely  divided  matter,  of  which  11  parts 
were  carbonate  of  lime,  and  9  parts  vegetable  matter, 
when  dried  at  212°,  gained  in  an  hour  by  exposure  to 
air  saturated  with  moisture,  at  temperature  62°,  18 
grains. 

1000  parts  of  a  very  fertile  soil  from  the  banks 
of  the  river  Parret,  in  Somersetshire,  under  the  same 
<:ircumstances,  gained  16  grains. 

1000  parts  of  a  soil  from  Mersea,  in  Essex, 
worth  45  shillings  an  acre,  gained  13  grains. 

1000  grains  of  a  fine  sand  from  Essex,  worth 
^8  shillings  an  acre,  gained  1 1  grains. 

1000  of  a  coarse  sand  worth  15  shillings  an  acre, 

gained  only  8  grains. 

1000  of  the  soil  of  Bagshot-heath  gained  only  .^ 
grains. 


[  164  ] 

Water,  and  the  decomposing  animal  and  vegeta- 
ble matter  existing  in  the  soil,  constitute  the  true 
nourishment  of  plants  ;  and  as  the  earthy  parts  of  the 
soil  are  useful  in  retaining  water,  so  as  to  supply  it 
in  the  proper  proportions  to  the  roots  of  the  vegeta- 
bles, so  they  are  likewise  efficacious  in  producing  the 
proper  distribution  of  the  animal  or  vegetable  matter ; 
when  equally  mixed  with  it  they  prevent  it  from  de- 
composing too  rapidly  ;  and  by  their  means  the  solu- 
ble parts  are  supplied  in  proper  proportions. 

Besides  this  agency,  which  may  be  considered  as 
mechanical,  there  is  another  agency  between  soils  and 
organizable  matters,  which  may  be  regarded  as  che- 
mical in  its  nature.  The  earths,  and  even  the  earthy 
carbonates,  have  a  certain  degree  of  chemical  attrac- 
tion for  many  of  the  principles  of  vegetable  and  ani- 
mal substances.  This  is  easily  exemplified  in  the  in- 
stance of  alumina  and  oil ;  if  an  acid  solution  of  alu- 
mina be  mixed  with  a  solution  of  soap,  which  consists 
of  oily  matter  and  potassa ;  the  oil  and  the  alumina 
will  unite  and  form  a  white  powder,  which  will  sink 
to  the  bottom  of  the  fluid. 

The  extract  from  decomposing  vegetable  matter 
when  boiled  with  pipe-clay  or  chalk,  forms  a  combina- 
tion by  which  the  vegetable  matter  is  rendered  more 
difficult  of  decomposition  and  of  solution.  Pure  silica 
and  siliceous  sands  have  little  action  of  this  kind  ;  and 
the  soils  which  contain  the  niost  alumina  and  carbon- 
ate of  lime,  are  these  which  act  with  the  greatest  che- 
mical energy  in  preserving  manures.  Such  soils 
merit  the  appellation  which  is  commonly  given  to  them 


[         165         ] 

of  rich  sails  ;  for  the  vegetable  nourishment  is  long 
preserved  in  them,  unless  taken  up  by  the  organs  of 
plants.  Siliceous  sands,  on  the  contrary,  deserve  the 
term  hungry,  which  is  commonly  applied  to  them  ;  for 
the  vegetable  and  animal  matters  they  contain  not  be- 
ing attracted  by  the  earthy  constituent  parts  of  the 
soil,  are  more  liable  to  be  decomposed  by  the  action  of 
the  atmosphere,  or  carried  off  from  them  by  water. 

In  most  of  the  black  and  brown  rich  vegetable 
moulds,  the  earths  seem  to  be  in  combination  with  a 
peculiar  extractive  matter,  afforded  during  the  decom- 
position of  vegetables  :  this  is  slowly  taken  up,  or  at- 
tracted from  the  earths  by  water,  and  appears  to  con- 
stitute a  prime  cause  of  the  fertility  of  the  soil. 

The  standard  of  fertility  of  soils  for  different 
plants  must  vary  with  the  climate  ;  and  must  be  parti- 
cularly influenced  by  the  quantity  of  rain. 

The  power  of  soils  to  absorb  moisture  ought  to 
be  much  greater  in  warm  or  dry  counties,  than  in  cold 
and  moist  ones  ;  and  the  quantity  of  clay,  or  vegeta- 
ble or  animal  matter  they  contain  greater.  Soils  also 
on  declivities  ought  to  be  more  absorbent  than  in 
plains  or  in  the  bottom  of  vallies.  Their  productive- 
ness likewise  is  influenced  by  the  nature  of  the  sub- 
soil or  the  stratum  on  which  they  rest. 

When  soils  are  immediately  situated  upon  a  bed 
of  rock  or  stone,  they  are  much  sooner  rendered  dry 
by  evaporation,  than  where  the  subsoil  is  of  clay  or 
marie ;  and  a  prime  cause  of  the  great  fertility  of  the 
land  in  the  moist  climate  of  Ireland,  is  the  proximity 
of  the  rocky  strata  to  the  soil. 


t  166         3 

A  clayey  subsoil  will  sometimes  be  of  material 
advantage  to  a  sandy  soil;  and  in  this  case  it  will  re- 
tain moisture  in  such  a  manner  as  to  be  capable  of 
supplying  that  lost  by  the  earth  above,  inconsequence 
of  evaporation,  or  the  consumption  of  it  by  plants. 

A  sandy,  or  gravelly  subsoil,  often  corrects  the 
imperfections  of  too  great  a  degree  of  absorbent  power 
in  the  true  soil. 

In  calcareous  countries,  where  the  surface  is  a 
species  of  marie,  the  soil  is  often  found  only  a  few 
inches  above  the  limestone;  and  its  fertility  is  not  im- 
paired by  the  proximity  of  the  rock;  though  in  a  less 
absorbent  soil,  this  situation  would  occasion  barren- 
ness; and  the  sandstone  and  limestone  hills  in  Derby- 
shire and  North  Wales,  may  be  easily  distinguished  at 
a  distance  in  summer  by  the  different  tints  of  the  ve- 
getation. The  grass  on  the  sandstone  hills  usually 
appears  brown  and  burnt  up;  that  on  the  limestone 
hills,  flourishing  and  green. 

In  devoting  the  different  parts  of  an  estate  to  the 
necessary  crops,  it  is  perfectly  evident  from  what  has 
been  said,  that  no  general  principle  can  be  laid  down, 
except  when  all  the  circumstances  of  the  nature,  com- 
position, and  situation  of  the  soil  and  subsoil  are 
known. 

The  methods  of  cultivation  likewise  must  be  dif- 
ferent for  different  soils.  The  same  practice  which  will 
be  excellent  in  one  case  may  be  destructive  in  another. 

Deep  plougliing  may  be  a  very  profitable  practice 
in  a  rich  thick  soil;  and. in  a  fertile  shallow  soil,  situa- 
ted upon  cold  clay  or  sandy  subsoil,  it  may  be  ex- 
tremely prejudicial. 


C         167         ] 

In  a  moist  climate  where  the  quantity  of  rain  that 
falls  annually  equals  from  40  to  60  inches,  as  in  Lan- 
cashire,  Cornwall,  and  some  parts  of  Ireland,  a  silice- 
ous sandy  soil  is  much  more  productive  than  in  dry 
districts;  and  in  such  situations,  wheat  and  beans  will 
require  a  less  coherent  and  absorbent  soil  than  in 
drier  situations;  and  plants  having  bulbous  roots,  will 
flourish  in  a  soil  containing  as  much  as  14  parts  out 
of  15  of  sand. 

Even  the  exhausting  powers  of  crops  will  be  in- 
fluenced by  Hke  circumstances.  In  cases  where  plants 
cannot  absorb  sufficient  moisture,  they  must  take  up 
more  manure.  And  in  Ireland,  Cornwall,  and  the 
WTStern  Highlands  of  Scotland,  corn  will  exhaust  less 
than  in  dry  inlaiTd  situations.  Oats,  particularly  in 
dry  climates,  are  impoverishing  in  a  much  higher  de- 
gree than  in  moist  ones. 

Soils  appear  to  have  been  originally  produced  in 
consequence  of  the  decomposition  of  rocks  and  strata. 
It  often  happens  that  soils  are  found  in  an  unaltered 
state  upon  the  rocks  from  w^hich  they  were  derived. 
It  is  easy  to  form  an  idea  of  the  manner  in  which 
rocks  are  converted  into  soils,  by  referring  to  the  in- 
stance of  soft  granite^  or  procelain  gra?2ite.  This  sub- 
stance consists  of  three  ingredients,  quartz,  feldspar, 
and  mica.  The  quartz  is  almost  pure  siliceous  earth, 
in  a  crystalline  form.  The  feldspar  and  mica  are  very 
compounded  substances;  both  contain  silica,  alumina, 
and  oxide  of  iron;  in  the  feldspar  there  is  usually 
lifn*e  and  pot^tssa;  in  the  mica,  lime  and  magnesia. 


C         168         3 

When  a  granitic  rock  of  this  kind  has  been  long 
exposed  to  the  influence  of  air  and  water,  the  lime 
and  the  potassa  contained  in  its  constituent  parts  are 
acted  upon  by  water  or  carbonic  acid;  and  the  oxide 
of  iron,  which  is  almost  always  in  its  least  oxided  state, 
tends  to  combine  with  more  oxygene;  the  consequence 
is,  that  the  feldspar  decomposes,  and  likewise  the 
mica;  but  the  first  the  most  rapidly.  The  feldspar, 
which  is  as  it  were  the  cement  of  the  stone,  forms  a 
fine  clay:  the  mica  partially  decomposed  mixes  with 
it  as  sand;  and  the  undecomposed  quartz  appears  as 
gravel,  or  sand  of  different  degrees  of  fineness. 

As  soon  as  the  smallest  layer  of  earth  is  formed  on 
the  surface  of  a  rock,  the  seeds  of  Hchens,  mosses,  and 
other  imperfect  vegetables  which  are  constantly  float- 
ing in  the  atmosphere,  and  which  have  made  it  their 
resting  place,  begin  to  vegetate;  their  death,  decompo- 
sition, and  decay  afford  a  certain  quantity  of  organi- 
zable  matter,  which  mixes  with  the  earthy  materials  of 
the  rock;  in  this  improved  soil  more  perfect  plants  are 
capable  of  subsisting;  these  in  their  turn  absorb  nour- 
ishment from  water  and  the  atmosphere;  and  after  per- 
ishing afford  new  materials  to  those  already  provided: 
the  decomposition  of  the  rock  still  continues;  and  at 
length  by  such  slow  and  gradual  processes,  a  soil  is 
formed  in  which  even  forest  trees  can  fix  their  roots, 
and  which  is  fitted  to  reward  the  labours  of  the  culti- 
vator. 

In  instances  where  successive  generations  of  vege- 
tables have  grown  upon  a  soil,  unless  part  of  their  pro- 
duce has  been  carried  off  by  man,  or  consumed  by 


£      169      3 

animals,  the  vegetable  matter  increases  in  such  a  pro- 
portion, that  the  soil  approaches  to  a  peat  in  its  na- 
ture ;  and  if  in  a  situation  where  it  can  receive  water 
from  a  higher  district,  it  becomes  spongy,  and  per- 
meated with  that  fluid  and  is  gradually  rendered  in- 
capable of  supporting  the  nobler  classes  of  Vegetables. 

Many  peat-mosses  seem  to  have  been  formed  by 
the  destruction  of  forests,  in  consequence  of  the  impru- 
dent use  of  the  hatchet  by  the  early  cultivators  of  the 
country  in  which  they  exist :  when  the  trees  are  fel- 
led in  the  out-skirts  of  a  wood,  those  in  the  interior  ex- 
posed to  the  influence  of  the  winds ;  and  having  been 
accustomed  to  shelter,  become  unhealthy,  and 
die  in  their  new  situation;  and  their  leaves  and 
branches  gradually  decomposing,  produce  a  stratum 
of  vegetable  matter.  In  many  of  the  great  bogs  in 
Ireland  and  Scotland,  the  larger  trees  that  are  found 
in  the  out-skirts  of  them,  bear  the  marks  of  having 
been  felled.  In  the  interior,  few  entire  trees  are 
found  ;  and  the  cause  is,  probably,  that  they  fell  by 
gradual  decay  ;  and  that  the  fermentation  and  decom- 
position of  the  vegetable  matter  was  most  rapid  where 
it  was  in  the  greatest  quantity. 

Lakes  and  pools  of  water  are  some  times  jfilled 
up  by  the  accumulation  of  the  remains  of  acquatic 
plants ;  and  in  this  case  a  sort  of  spurious  peat  is 
formed.  The  fermentation  in  these  cases,  however, 
seems  to  be  of  a  different  kind.  Much  more  gaseous 
matter  is  evolved ;  and  the  neighbourhood  of  moras- 
ses in  which  aquatic  vegetables  decompose,  is  usually 
aguish  and  unhealthy ;  whilst  that  of  the  true  peat,  or 


C      ivo      ] 

peat  forqjed  on  soils  originally  dry,  is  always  salu- 
brious. 

The  earthy  matter  of  peats  is  uniformly  analo- 
gous to  that  of  the  stratum  on  which  they  repose  ;  the 
plants  which  have  formed  them  must  have  derived 
the  earths  that  they  contained  from  this  stratum. 
Thus  in  Wiltshire  and  Berkshire,  where  the  stratum 
below  the  peat  is  chalk,  calcareous  earth  abounds  in 
the  ashes,  and  very  little  alumina  and  silica.  They 
likewise  contain  much  oxide  of  iron  and  gypsum,  both 
of  which  may  be  derived  from  the  decomposition  of 
the  pyrites,  so  abundant  in  chalk. 

Different  specimens  of  peat  that  I  have  burnt, 
from  the  granitic  and  schistose  soils  of  different  parts 
of  these  islands  have  always  given  ashes  principally 
siliceous  and  aluminous  and  a  specimen  of  peat  from 
the  county  of  Antrim,  gave  ashes  which  afforded  very 
nearly  the  same  constituents  as  the  great  basaltic  stra- 
tum of  the  county. 

Poor  and  hungry  soils,  such  as  are  produced 
from  the  decomposition  of  granitic  and  sandstone 
rocks,  remain  very  often  for  ages  with  only  a  thin  co- 
vering of  vegetation.  Soils  from  the  decomposition 
of  limestone,  chalks,  and  basalts  are  often  clothed  by 
nature  with  the  perennial  grasses  ;  and  afford,  when, 
ploughed  up,  a  rich  bed  of  vegetation  for  every  species 
of  cxiltivated  plant. 

Rocks  and  strata  from  which  soils  have  been  de» 
rived,  and  those  which  compose  the  more  interior 
solid  parts  of  the  globe,  are  arranged  in  a  certain  or- 
der ;  and  as  it  often  happens  that  strata  very  different 


C      ni      ] 

in  their  nature  are  associated  together,  and  that  the 
strata  immediately  beneath  the  soil  contain  materials 
which  may  be  of  use  for  improving  it,  a  general  view 
of  the  nature  and  position  of  rocks  and  strata  in  na- 
ture, will  not,  I  trust,  be  unacceptable  to  the  scientific 
farmer. 

Rocks  are  generally  divided  by  geologists  into 

two  grand  divisions,  distinguished  by  the  names  of 
•primary  and  secondary. 

The  primary  rocks  are  composed  of  pure  crystal- 
line matter,  and  contain  no  fragments  of  other  rocks. 

The  secondary  rocks,  or  strata,  consist  only  part- 
ly of  crystalline  matter  ;  contain  fragments  of  other 
rocks  or  strata  j  often  abound  in  the  remains  of  vege- 
tables and  marine  animals ;  and  sometimes  contain 
the  remains  of  land  animals. 

The  primary  rocks  are  generally  arranged  in 
large  masses,  or  in  layers  vertical,  or  more  or  less 
inclined  to  the  horizon. 

The  secondary  rocks  are  usually  disposed  in 
strata  or  layers,  parallel,  or  nearly  parallel  to  the 
horizon. 

The  number  of  primary  rocks  which  are  com- 
monly observed  in  nature  are  eight. 

First,  granite,  which,  as  has  been  mentioned,  is 
composed  of  quartz,  feldspar,  and  mica  ;  when  these 
bodies  are  arranged  in  regular  layers  in  the  rock,  it  is 
called  gneis. 

Second,  micaceous  schistus,  which  is  composed  of 
quartz  and  mica  arranged  in  layers,  which  are  usually 
curvilineal. 


Third,  sienitef  which  consists  of  the  substance 
called  hornblende  and  feldspar. 

Fourth,  serpentine,  which  is  constituted  by  feld-^ 
spar  and  a  body  named  resplendent  hornblende ;  and 
their  separate  crystals  are  often  so  small  as  to  give 
the  stone  a  uniform  appearance :  this  rock  abounds 
in  veins  of  a  substance  called  steatite,  or  soap  rock. 

Fifth,  porphyry,  which  constists  of  crystals  of 
feldspar,  embedded  in  the  same  material,  but  usually 
©f  a  different  colour. 

Sixth,  granular  marble,  which  consists  entirely 
of  crystals  of  carbonate  of  lime  ;  and  which,  when  its 
colour  is  white,  and  texture  fine,  is  the  substance  used 
by  statuaries. 

Seventh,  chlorite  schist,  which  consists  of  chlo» 
rite,  a  green  or  grey  substance  somewhat  analogous 
to  mica  and  feldspar. 

Eight,  quartzose  rock,  which  is  composed  of 
quartz  in  a  granular  form,  sometimes  united  to  small 
quantities  of  the  crystalline  elements,  which  have 
been  mentioned  as  belonging  to  the  other  rocks. 

The  secondary  rocks  are  more  numerous  than 
the  primary  ;  but  twelve  varieties  include  all  that  are 
usually  found  in  these  islands* 

First,  grauwacke,  which  consists  of  fragments  of 
quart2;,  or  chlorite  schist,  embedded  in  a  cement, 
principally  composed  of  feldspar. 

Second,  siliceous  sandstone,  which  is  composed  of 
fine  quarts  or  sand,  united  by  a  siliceous  cement. 

Third,  limestone,  consisting  of  carbonate  of  lime, 
more  compact  in  its  texture  than  in  the  granular  mar- 
ble I  and  often  abounding  in  marine  exuvia* 


Fourth,  aluminous  schist,  or  shale^  consisting  of 
the  decomposed  materials  of  different  rocks  cemented 
by  a  small  quantity  of  ferruginous  or  siliceous  matter; 
and  often  containing  the  impressions  of  vegetables. 

Fifth,  calcareous  sandstone^  which  is  calcareous 
sand,  cemented  by  calcareous  matter* 

Sixth,  irone  stone ^  formed  of  nearly  the  same  ma- 
terials ^  aluminous  schist,  or  shale  \  but  containing  a 
much  larger  quantity  of  oxide  or  iron. 

Seventh,  basalt  or  whinstone,  which  consists  of 
feldspar  and  hornblende  with  materials  derived  from 
the  decomposition  of  the  primary  rocksj  the  crystals 
are  generally  so  small  as  to  give  the  rock  a  homo- 
geneous appearance;  and  it  is  often  disposed  in  very 
regular  columns,  having  usually  five  or  six  sides. 

Eighth,  bituminous  or  common  coaL 

Ninth,  gypsum,  the  substance  so  well  known  by 
that  name,  which  consists  of  sulphate  of  lime;  and  of- 
ten contains  sand. 

Tenth,  rock  salt. 

Eleventh,  chalk,  which  usually  abounds  in  re- 
mains of  marine  animals,  and  contains  horizontal 
layers  of  flints. 

Twelfth,  plum-pudding  stone,  consisting  of  pebbles 
cemented  by  a  ferruginous  or  siliceous  cement. 

To  describe  more  particularly  the  constituent 
parts  of  the  different  rocks  and  strata  will  be  unneces^. 
sary;  at  any  time,  indeed,  details  on  this  subject  are 
useless,  unless  the  specimens  are  examined  by  the 
eye;  and  a  close  mspection  and  comparison  of  the  dif* 


C  174  J 

ferent  species,  will,  in  a  short  time,   enable  the  most 
common  observer  to  distinguish  them. 

The  highest  mountains  in  these  islands,  and  in- 
deed in  the  whole  of  the  old  continent,  are  constituted 
by  granite;  and  this  rock  has  likev/ise  been  found  at 
the  greatest  depths  to  which  the  industry  of  man  has 
*is  yet  been  able  to  penetrate;  micaceous  schist  is  often 
found  immediately  upon  granite;  serpentine  or  marble 
upon  micaceous  schist:  but  the  order  in  which  the 
primary  rocks  are  grouped  together  is  various.  Mar- 
ble and  serpentine  are  usually  found  uppermost;  but 
granite,  though  it  seems  to  form  the  foundation  of  the 
rocky  strata  of  the  globe,  is  yet  sometimes  discovered 
above  micaceous  schist. 

The  secondry  rocks  are  always  incumbent  on  the 
primary;  the  lowest  of  them  is  usually  grauwacke:  up- 
on this,  limestone  or  sandstone  is  often  found;  coal 
generally  occurs  between  sandstone  or  shale;  basalt 
often  exists  above  sandstone  and  limestone;  rock  salt 
almost  always  occurs  associated  with  red  sandstone 
and  gypsum.  Coal,  basalt,  sandstone,  and  limestone, 
are  often  arranged  in  different  alternate  layers,  of  no 
considerable  thickness,  so  as  to  form  a  great  extent  of 
country.  In  a  depth  of  less  than  500  yards,  80  of 
these  different  alternate  strata  have  been  counted. 

The  veins  which  afford  metallic  substances,  are 
fissures  more  or  less  vertical,  filled  with  a  material 
different  from  the  rock  in  which  they  exist.  This 
material  is  almost  always  crystalline;  and  usually  con- 
sists of  calcareous  spar,  fluor  spar,  quartz,  or  heavy 
spar,  either  separate  or  together.     The  metallic  sub- 


f^ 


^1  ? 


11-^  "I 

a;i    ^    0,    Rj 

>^     '^        "^        !S 


I. 


5j 

11 


■I   "< 


I   I 

Co     K^ 


C     ,K     '^    -S 

'C    'n5   .-^   "^S 
^     0(   v^    >    ^  ^ 


C         175        3 

Stances  are  generally  dispersed  through,  or  confusedly 
mixed  with  these  crystalline  bodies.  The  veins  in 
hard  granite  seldom  afford  much  useful  metal j  but  in 
the  veins  in  soft  granite,  and  in  gneis,  tin,  copper,  and 
lead  are  found.  Copper  and  iron  are  the  only  metals 
usually  found  in  the  veins  in  serpentine.  Micaceous 
schist,  sienite,  and  granular  marble,  are  seldom  me- 
talliferous rocks.  Lead,  tin,  copper,  iron,  and  many 
other  metals  are  found  in  the  veins  in  chlorite  schist. 
Grauwacke,  when  it  contains  few  fragments  and  exists 
in  large  masses,  is  often  a  metalliferous  rock.  The 
precious  metals,  likewise  iron,  lead,  and  antimony,  are 
found  in  it;  and  sometimes  it  contains  veins  or  masses 
of  stone  coal,  or  coal  free  from  bitumen.  Limestone 
is  the  great  metalliferous  rock  of  the  secondary  family; 
and  lead  and  copper  are  the  metals  most  usually  found 
in  it.  No  metallic  veins  have  ever  been  found  in 
shale,  chalk,  or  calcareous  sandstone;  and  they  are 
very  rare  in  basalt  and  siliceous  sandstone.* 

In  cases  where  veins  in  rocks  are  exposed  to  the 
atmosphere,  indications  of  the  metals  they  contain  may 
be  often  gained  from  their  superficial  appearance. 
Whenever  fluor  spar  is  found  in  a  vein,  there  is  al- 
ways strong  reason  to  suspect  that  it  is  associated 
with  metallic  substances*  A  brown  powder  at  the 
surface  of  a  vein  always  indicates  iron,  and  often  tin; 
a  pale  yellow  powder  lead;  and  a  green  colour  in  a 
vein  denotes  the  presence  of  copper. 


*  Fig.  16,  win  give  a  general  idraof  the  apptarance  ami  arrangement  of  rofks 

and  veins. 


C        176        ] 

It  may  not  be  improper  to  give  a  general  descrip- 
tion of  the  geological  constitution  of  Great  Britain  and 
Ireland.  Granite  forms  the  great  ridge  of  hills  ex- 
tending from  Land's  End  through  Dartmoor  into  De- 
vonshire. The  highest  rocky  strata  in  Somersetshire 
are  grauwacke  and  limestone.  The  Malvern  hills  are 
composed  of  granite,  sienite,  and  porphyry.  The 
highest  mountains  in  Wales  are  chlorite  schist,  or 
grauwacke.  Granite  occurs  at  mount  Sorrel  in  Lei- 
cestershire. The  great  range  of  the  mountains  in 
Cumberland  and  Westmoreland,  are  porphyry,  chlo- 
rite schist,  and  grauwacke;  but  granite  is  found  at  their 
western  boundary.  Throughout  Scotland  the  most 
elevated  rocks  are  granite,  sienite,  and  micaceous 
schistus.  No  true  secondary  formations  are  found  in 
South  Britain,  west  of  Dartmoor;  and  no  basalt  south 
of  the  Severn.  The  chalk  district  extends  from  the 
western  part  of  Dorsetshire,  to  the  eastern  coast  of 
Norfolk.  The  coal  formations  abound  in  the  district 
between  Glamorganshire  and  Derbyshire;  and  like- 
wise in  the  secondary  strata  of  Yorkshire,  Durham, 
Westmoreland,  and  Northumberland.  Serpentine  is 
found  only  in  three  places  in  Great  Britain;  near  Gape 
Lizard  in  Cornwall,  Portsoy  in  Aberdeenshire,  and  in 
Ayrshire.  Black  and  grey  granular  marble  is  found 
near  Padstow  in  Cornwall;  and  other  coloured  primary 
marbles  exist  in  the  neighbourhood  of  Plymouth. 
Coloured  primary  marbles  are  abundant  in  Scotland; 
and  white  granular  marble  is  found  in  the  Isle  of  Sky, 
in  Assynt,  and  on  the  banks  of  Loch  Shin  in  Suther- 
land: the  principle  coal  formations  in  Scotland  are  in 


C       n7      ] 

Dumbartonshire.  Ayrshire,  Fifeshire,  and  on  'the 
banks  of  the  Brora  in  Sutherland.  Secondary  lime- 
stone and  sandstone  are  found  in  most  of  the  low 
countries  north  of  the  Mendip  hills. 

In  Ireland  there  are  five  great  associations  of  pri- 
mary  mountains  ;  the  mountains  of  Morne  in  the 
county  of  Down  ;  the  mountains  of  Donegal ;  those 
of  Mayo  and  Galway,  those  of  Wicklow,  and  those 
of  Kerry.  The  rocks  composing  the  four  first  of 
these  mountain  chains  are  principally  granite,  gneis, 
sienite,  micaceous  schist,  and  porphyry.  The  moun- 
tains of  Kerry  are  chiefly  constituted  by  granular 
quartz,  and  chlorite  schist.  Coloured  marble  is  found 
near  Killarney;  and  white  marble  on  the  western  coast 
of  Donegal. 

Limestone  and  sandstone  are  the  common  secon- 
dary rocks  found  south  of  Dublin.  In  Sligo,  Ros* 
common,  and  Leitrim,  hmestone,  sandstone,  shale,  iron 
stone,  and  bituminous  coal  are  found.  The  second- 
ary hills  in  these  counties  are  of  considerable  eleva- 
tion ;  and  many  of  them  have  basaltic  summits.  The 
northern  coast  of  Ireland  is  principally  basalt  ;  this 
rock  commonly  reposes  upon  a  white  limestone,  con- 
taining layers  of  flint,  and  the  same  fossils  as  chalk  ; 
but  it  is  considerably  harder  than  that  rock.  There 
are  some  instances,  in  this  district,  in  which  columnar 
basalt  is  found  above  sandstone  and  shale,  alternating 
with  coal.  The  stone  coal  of  Ireland  is  principally 
found  in  Kilkenny,  associated  with  Hmestone  and 
grauwacke. 

A  2 


C      178      3 

It  is  evident  from  what  has  been  said  concerning 
the  production  of  soils  from  rocks,  that  there  must  be 
at  least  as  many  varieties  of  soils  as  there  are  species 
of  rocks  exposed  at  the  surface  of  the  earth  ;  in  fact 
there  are  many  more.  Independent  of  the  changes 
produced  by  cultivation  and  the  exertions  of  human 
labour,  the  materials  of  strata  have  been  mixed  to- 
gether and  transported  from  place  to  place  by  various 
great  alterations  that  have  taken  place  in  the  system 
of  our  globe,  and  by  the  constant  operation  of  water. 

To  attempt  to  class  soils  with  scientific  accuracy, 
would  be  a  vain  labour ;  the  distinctions  adopted  by 
farmers  are  sufficient  for  the  purposes  of  agriculture  ; 
particularly  if  some  degree  of  precision  be  adopted  in 
the  application  of  terms.  The  term  sandy,  for  instance, 
should  never  be  applied  to  any  soil  that  does  not  con- 
tain at  least  J  of  sand  ;  sandy  soils  that  effervesce  with 
acids  should  be  distinguished  by  the  name  of  calcare- 
ous sandy  soil,  to  distinguish  them  from  those  that 
are  siliceous.  The  term  clayey  soil  should  not  be 
applied  to  any  land  which  contains  less  than  i.  of  im- 
palpable earthy  matter,  not  considerably  effervescing 
with  acids  :  the  word  loam  should  be  limited  to  soils, 
containing  at  least  one  third  of  impalpable  earthy  mat- 
ter, copiously  effervescing  with  acids.  A  soil  to  be 
considered  as  peaty,  ought  to  contain  at  least  one  half 
of  vegetable  matter. 

In  cases  where  the  earthy  part  of  a  soil  evidently 
consists  of  the  decomposed  matter  of  one  particular 
rock,  a  name  derived  from  the  rock  may  with  propriety 
be  applied  to  it.     Thus,  if  a  fine  red  earth  be  found 


C         179         3 

immediately  above  decomposing  basalt,  it  may  be  de- 
nominated basaltic  soil.  If  fragments  of  quartz  and 
mica  be  found  abundant  in  the  materials  of  the  soil, 
which  is  often  the  case,  it  may  be  denominated  granitic 
soil ;  and  the  same  principles  may  be  applied  to  other 
like  instances. 

In  general,  the  soils,  the  materials  of  which  are 
the  most  various  and  heterogenous,  are  those  called 
alluvial,  or  which  have  been  formed  from  the  deposi- 
tions of  rivers  ;  many  of  them  are  extremely  fertile. 
I  have  examined  some  productive  alluvial  soils,  which 
have  been  very  different  in  their  composition.  The 
soil  which  has  been  mentioned  page  163,  as  very  pro- 
ductive, from  the  banks  of  the  river  Parret  in  Somer- 
setshire, afforded  me  eight  parts  of  finely  divided 
earthy  matter,  and  one  part  of  siliceous  sand  ;  and  an 
analysis  of  the  finely  divided  matter  gave  the  follow- 
ing results. 

360  parts  of  carbonate  of  lime, 

25 alumina, 

20 silica, 

8 oxide  of  iron. 

19 vegetable,  animal,  and  saline  matter. 

A  rich  soil  from  the  neighbourhood  of  the  Avon, 
in  the  valley  of  Evesham  in  Worcestershire,  afforded 
me  three  fifths  of  fine  sand,  and  two  fifths  of  impalpa- 
ble matter ;  the  impalpable  matter  consisted  of, 
35  Alumina, 
41  Silica, 

14  Carbonate  of  lime, 
3  Oxide  of  iron, 
7  Vegetable,  animal,  and  saline  matter. 


[  180         ] 

A  specimen  of  good  soil  from  Tiviot-dale,  afford- 
ed five  sixths  of  fine  siliceous  sand,  and  one  sixth  of 
impalpable  matter ;  which  consisted  of 

41  Alumina, 

42  Silica, 

4  Carbonate  of  lime, 

5  Oxide  of  iron, 

S  Vegetable,  animal,  and  saline  matter. 
A  soil  yielding  excellent  pasture  from  ifie  valley 
of  the  Avon,  near  Salisbury,  afforded  one  eleventh  of 
coarse  siliceous  sand ;  and  the  finely  divided  matter 
consisted  of 

7  Alumina, 
14  Silica, 

63  Carbonate  of  lime,         •- 
2  Oxide  of  iron, 

14  Vegetable,  animal,  and  saline  matter- 
In  all  these  instances  the  fertility  seems  to  de- 
pend upon  the  state  of  division,  and  mixture  of  the 
earthy  materials  and  the  vegetable  and  animal  matter  j 
and  may  be  easily  e^Jplained  on  the  principles  v^^hich  I 
have  endeavoured  to  elucidate  in  the  preceding  part 
of  this  Lecture. 

In  ascertaining  the  composition  of  sterile  soils 
with  a  view  to  their  improvement,  any  particular 
ingredient  which  is  the  cause  of  their  unproduc- 
tiveness, should  be  particularly  attended  to ;  if  possi- 
ble, they  should  be  compared  with  fertile  soils  in  the 
same  neighbourhood,  and  in  similar  situations,  as  the 
difference  of  the  composition  may,  in  many  cases,  in- 
dicate the  most  proper  methods  of  improvement.     If 


I         181         3 

on.  washing  a  sterile  soil  it  is  found  to  contain  the  "salts 
of  iron,  or  any  acid  matter,  it  may  be  ameliorated  by 
the  application  of  quick  lime.  A  soil  of  good  ap- 
parent texture  from  Lincolnshire,  was  put  into  my 
hands  by  Sir  Joseph  Banks  as  remarkable  for  steril- 
ity :  on  examining  it,  I  found  that  it  contained  sul- 
phate of  iron  ;  and  I  offered  the  obvious  remedy  of 
top  dressing  with  lime,  which  converts  the  sulphate 
into  a  manure.  If  there  be  an  excess  of  calcareous 
matter  in  the  soil,  it  may  be  improved  by  the  applica- 
tion of  sand,  or  clay.  Soils  too  abundant  in  sand  are 
benefited  by  the  use  of  clay,  or  marie,  or  vegetable 
matter.  A  field  belonging  to  Sir  Robert  Vaughan  at 
Nannau,  Merionethshire,  the  soil  of  which  was  a  light 
sand,  was  much  burnt  up  in  the  summer  of  I S05  j  I 
recommended  to  that  gentleman  the  application  of  peat 
as  a  top  dressing.  The  experiment  was  attended 
with  immediate  good  effects  ;  and  Sir  Robert  last  year 
informed  me,  that  the  benefit  was  permanent.  A  de- 
ficiency of  vegetable  or  animal  matter  must  be  sup- 
plied by  manure.  An  excess  of  vegetable  matter  is 
to  be  removed  by  burning,  or  to  be  remedied  by  the 
application  of  earthy  materials.  The  improvement  of 
peats,  or  bogs,  or  marsh  lands,  must  be  preceded  by 
draining ;  stagnant  water  being  injurious  to  all  the 
nutritive  classes  of  plants.  Soft  black  peats,  when 
drained,  are  often  made  productive  by  the  mere  appli- 
cation of  sand  or  clay  as  a  top  dressing.  When  peats 
are  acid,  or  contain  ferruginous  salts,  calcareous  mat- 
ter is  absolutely  necessary  in  bringing  them  into  culti- 
vation.   When  they  abound  in  the  branches  and  roots 


[  182  ] 

of  trees,  or  when  their  surface  entirely  consists  of  liv- 
ing vegetables,  the  wood  or  the  vegetables  must  either 
by  carried  off,  or  be  destroyed  by  burning.  In  the 
last  case  their  ashes  afford  earthy  ingredients,  fitted  to 
improve  the  texture  of  the  peat. 

The  best  natural  soils  are  those  of  which  the  ma- 
terials have  been  derived  from  different  strata;  which 
have  been  minutely  divided  by  air  and  water,  and  are  in- 
timately blended  together:  and  in  improving  soils  arti- 
ficially, the  farmer  cannot  do  better  than  imitate  the 
processes  of  nature. 

The  materials  necessary  for  the  purpose  are  sel- 
dom  far  distant:  coarse  sand  is  often  found  immedi- 
ately on  chalk;  and  beds  of  sand  and  gravel  are 
common  below  clay.  The  labour  of  improving  the 
texture  or  constitution  of  the  soil,  is  repaid  by  a  great 
permanent  advantage;  less  manure  is  required,  and  its 
fertility  insured:  and  capital  laid  out  in  this  way  secures 
for  ever,  the  productiveness,  and  consequently  the 
value  of  the  land. 


183 


LECTURE  V. 

On  the  nature  and  Constiution  of  the  Atmosphere;  and 
its  Influence  on  Vegetables.  Of  the  Germination  of 
Seeds.  Of  the  Functions  of  Plants  in  their  differ^ 
ent  Stages  of  Growth;  with  a  general  view  of  the 
Progress  ofVegetation. 

The  constitution  of  the  atmosphere  has  been  al- 
ready generally  referred  to  in  the  preceding  Lectures. 
Water,  carbonic  acid  gas,  oxygene,  and  azote,  have 
been  mentioned  as  the  principal  substances  compo- 
sing  it;  but  more  minute  enquiries  respecting  their  na- 
ture and  agencies  are  necessary  to  afford  correct 
views  of  the  uses  of  the  atmosphere  in  vegetation. 

On  these  enquiries  I  now  propose  to  enter;  the 
pursuit  of  them,  I  hope,  will  offer  some  objects  of 
practical  use  in  farming;  and  present  some  philosophi- 
cal  illustrations  of  the  manner  in  which  plants  are 
nourished;  their  organs  unfolded,  and  their  functions 
developed. 

If  some  of  the  salt  called  muriate  of  lime  that 
has  been  just  heated  red  be  exposed  to  the  air,  even 
in  the  driest  and  coldest  wheather,  it  will  increase  in 
weight  and  become  moist;  and  in  a  certain  time  will  be 
converted  into  a  fluid.  If  put  into  a  retort  and  heated, 
it  will  yield  pure  water;  will  gradually  recover  its 
pristine  state;  and,  if  heated  red,  its  former  weight:  so 
that  it  is  evident,  that  the  water  united  to  it  was  derived 


C  184  ] 

from  the  air.  And  that  it  existed  in  the  air  in  an  invis- 
ible and  elastic  form,  is  proved  by  the  circumstance, 
that  if  a  given  quantity  of  air  be  exposed  to  the 
salt;  its  volume  and  weight  will  diminish,  provided  the 
experiment  be  correctly  made. 

The  quantity  of  water  which  exists  in  air,  as  va- 
pour, varies  with  the  temperature.  In  proportion  as 
the  weather  is  hotter,  the  quantity  is  greater.  At  50° 
of  Fahrenheit  air  contains  about  ^V  of  its  volume  of 
vapour;  and  as  the  specific  gravity  of  vapour  is  to  that 
of  air  nearly  as  10  to  15,  this  is  about  tV  of  its  weight. 

At  100°,  supposing  that  there  is  a  free  commu- 
nication with  water,  it  contains  about  i\  parts  in  vol- 
ume, or  TT  in  weight.  It  is  the  condensation  of  va- 
pour by  diminution  of  the  temperature  of  the  atmos- 
phere, which  is  probably  the  principal  cause  of  the 

formation  of  clouds,  and  of  the  deposition  of  dew, 
mist,  snow,  or  hail. 

The  power  of  different  substances  to  absorb 
aqueous  vapour  from  the  atmosphere,  by  cohesive  at- 
traction was  discussed  in  the  last  Lecture.  The  leaves 
of  living  plants  appear  to  act  upon  the  vapour  likewise 
in  its  elastic  form,  and  to  absorb  it.  Some  vegetables 
increase  in  weight  from  this  cause,  when  suspended  in 
the  atmosphere  and  unconnected  with  the  soil;  such 
are  the  houseleek,-  and  different  species  of  the  aloe. 
In  very  intense  heats,  and  when  the  soil  is  dry,  the 
life  of  plants  seems  to  be  preserved  by  the  absorbent 
power  of  their  leaves:  and  it  is  a  beautiful  circumstance 
in  the  ceconomy  of  nature,  that  aqueous  vapour  is 
most  abundant  in  the  atmosphere  when  it  is  most  need* 


C  185  ] 

ed  for  the  purposes  of  life ;  and  that  when   other 
sources  of  its  supply  are  cut  off,  this  is  most  copious. 

The  compound  nature  of  water  has  been  referred 
to.  It  may  be  proper  to  mention  the  experimental 
proofs  of  its  decomposition  into,  and  composition 
from,  oxygene  and  hydrogene. 

If  the  metal  called  potassium  be  exposed  in  a 
glass  tube  to  a  small  quantity  of  w^ter,  it  will  act  upon 
it  with  great  violence ;  elastic  fluid  will  be  disengaged, 
which  will  be  found  to  be  hydrogene  ;  and  the  same  ef- 
fects will  be  produced  upon  the  potassium,  as  if  it  had 
absorbed  a  small  quantity  of  oxygene ;  and  the  hydro- 
gene disengaged,  and  the  oxygene  added  to  the  potas- 
sium are  in  weight  as  2  to  15  ;  and  if  two  in  volume  of 
hydrogene,  and  one  in  volume  of  oxygene,  which  have 
the  weights  of  2  and  15,  be  introduced  into  a  close  ves- 
sel, and  an  electrical  spark  passed  through  them,  they 
will  inflame  and  condense  into  17  parts  of  pure  water. 

It  is  evident  from  the  statements  given  in  the  third  ^ 
Lecture,  that  water  forms  by  far  the  greatest  part  of 
the  sap  of  plants  ;  and  that  this  substance,  or  its  ele- 
ments, enters  largely  into  the  constitution  of  their  or- 
gans and  solid  productions. 

Water  is  absolutely  necessary  to  the  ceconomy  of 
vegetation  in  its  elastic  and  fluid  state  ;  and  it  is  not 
devoid  of  use  even  in  its  solid  form.  Snow  and  ice 
are  bad  conductors  of  heat ;  and  when  the  ground  is 
covered  with  snow,  or  the  surface  of  the  soil  or  of 
water  is  frozen,  the  roots  or  bulbs  of  the  plants  be- 
neath are  protected  by  the  congealed  water  from  the 
influence  of  the  atmosphere,  the  temperature  of  which 

b2 


C       -is^       ] 

in  Northern  winters  is  usually  very  much  below  the 
freezing  point ;  and  this  water  becomes  the  first  nour- 
ishment of  the  plant  in  early  spring.  The  expansion 
of  water  during  its  congelation,  at  w^hich  time  its 
volume  increases  tV,  and  its  contraction  of  bulk  dur- 
ing a  thaw,  tend  to  pulverise  the  soil ;  to  separate  its 
parts  from  each  other,  and  to  make  it  more  permeable 
to  the  influence  of  the  air. 

If  a  solution  of  lime  in  water  be  exposed  to  the 
air,  a  pellicle  will  speedily  form  upon  it,  and  a  solid 
matter  will  gradually  fall  to  the  bottom  of  the  water, 
and  in  a  certain  time  the  water  will  become  tasteless  ; 
this  is  owing  to  the  conbination  of  the  lime,  which 
Was  dissolved  in  the  water,  with  carbonic  acid  gas 
which  existed  in  the  atmosphere,  as  may  be  proved 
by  collecting  the  film  and  the  solid  matter,  and  ignit^ 
ing  them  strongly  in  a  little  tube  of  platina  or  iron ; 
they  will  give  off  carbonic  acid  gas,  and  will  become 
quicklime,  which  added  to  the  same  water,  will  again 
bring  it  to  the  state  of  lime  water. 

The  quantity  of  carbonic  acid  gas  in  the  atmos- 
phere is  very  small.  It  is  not  easy  to  determine  it 
with  precision,  and  it  must  differ  in  different  situa- 
tions ;  but  where  there  is  a  free  circulation  of  air,  it 
is  probably  never  more  than  sio,  nor  less  than  uoo  of 
the  volume  of  air.  Carbonic  acid  gas  is  nearly  j  hea- 
vier than  the  other  elastic  parts  of  the  atmosphere  in 
their  mixed  state  :  hence  at  first  view  it  might  be  sup- 
posed that  it  would  be  most  abundant  in  the  lower 
regions  of  the  atmosphere  5  but  unless  it  has  been 
immediately  produced  at  the  surface  of  the  earth  ia 


[         187         ] 

some  chemical  process,  this  does  not  seem  to  be  the 
case  :  elastic  fluids  of  different  specific  gravities  have 
a  tendency  to  equable  mixture  by  a  species  of  attrac- 
tion, and  the  different  parts  of  the  atmosphere  are 
constantly  agitated  and  blended  together  by  winds  or 
other  causes.  De  Saussure  found  lime  water  preci- 
pitated on  Mount  Blanc,  the  highest  point  of  land  in 
Europe  ;  and  carbonic  acid  gas  has  been  always  found 
apparently  in  due  proportion,  in  the  air  brought  down 
from  great  heights  in  the  atmosphere  by  aerostatic 
adventurers. 

The  experimental  proofs  of  the  composition  of 
•carbonic  acid  gas  are  very  simple.  If  13  grains  of 
well  burnt  charcoal  be  inflamed  by  a  burning-glass  in 
100  cubical  inches  of  oxygene  gas,  the  charcoal  will 
entirely  disappear ;  and  provided  the  experiment  be 
correctly  made,  all  the  oxygene  except  a  few  cubical 
inches,  will  be  found  converted  into  carbonic  acid  j 
and  what  is  very  remarkable,  the  volume  of  the  gas  is 
not  changed.  On  this  last  circumstance  it  is  easy  to 
found  a  correct  estimation  of  the  quantity  of  pure 
charcoal  and  oxygene  in  carbonic  acid  gas :  the  weight 
of  100  cubical  inches  of  oxygene  gas  is  to  that  of  100 
cubical  inches  of  oxygene  gas,  as  47  to  34  :  so  that 
47  parts  in  weight  of  carbonic  acid  gas,  must  be 
composed  of  34  parts  of  oxygene  and  13  of  charcoal, 
which  correspond  with  the  numbers  given  in  the  se- 
x:ond  Lecture. 

Carbonic  acid  is  easily  decomposed  by  heating 
potassium  in  it ;  the  metal  combines  with  the  oxy- 
gene, and  the  charcoal  is  deposited  in  the  form  .of  a 
black  powder. 


L         188        3 

The  principal  consumption  of  the  carbonic  acid 
in  the  atmosphere,  seems  to  be  in  affording  nourish- 
ment to  plants  ;  and  some  of  them  appear  to  be  sup- 
plied with  carbon  chiefly  from  this  source. 

Carbonic  acid  gas  is  formed  during  fermentation, 
combustion,  putrefaction,  respiration,  and  a  number 
of  operations  taking  place  upon  the  surface  of  the 
earth  ;  and  there  is  no  other  process  known  in  nature 
by  which  it  can  be  destroyed  but  by  vegetation. 

After  a  given  portion  of  air  has  been  deprived  of 
aqueous  vapour  and  carbonic  acid  gas,  it  appears  little 
altered  in  its  properties  ;  it  supports  combustion  and 
animal  life.  There  are  many  modes  of  separating  its 
principal  constituents,  oxygene  and  azote,  from  each 
other.  A  simple  one  is  by  burning  phosphorus  in  a 
confined  volume  of  air :  this  absorbs  the  oxygene  and 
leaves  the  azote  ;  and  100  parts  in  volume  of  air,  in 
which  phosphorus  has  been  burnt,  yield  79  parts  of 
azote  J  and  by  mixing  this  azote  with  21  parts  of 
fresh  oxygene  gas  artifically  procured,  a  substance 
having  the  original  characters  of  air  is  produced.  To 
procure  pure  oxygene  from  air,  quicksilver  may  be 
kept  heated  in  it,  at  about  600°,  till  it  becomes  a  red 
powder  ;  this  powder,  when  ignited,  will  be  restored 
to  the  state  of  quicksilver  by  giving  off  oxygene. 

Oxygene  is  necessary  to  some  functions  of  vege- 
tables ;  but  its  great  importance  in  nature  is  in  its  rela- 
tion to  the  oeconomy  of  animals.  It  is  absolutely  ne- 
cessary to  their  life.  Atmospheric  air  taken  into  the 
lungs  of  animals,  or  passed  in  solution  in  water 
through  the  gills  of  fishes,  loses  oxygene  j  and  for 


C         189         ] 

the  oxygene  lost,  about  an  equal  volume  of  carbonic 
acid  appears. 

The  effects  of  azote  in  vegetation  are  not  distinct- 
ly known.  As  it  is  found  in  some  of  the  products  of 
vegetation,  it  may  be  absorbed  by  certain  plants  from 
the  atmosphere.  It  prevents  the  action  of  oxygene  from 
being  too  energetic,  and  serves  as  a  medium  in  which 
the  more  essential  parts  of  the  air  act;  nor  is  this  cir- 
cumstance unconformable  to  the  analogy  of  nature;  for 
the  elements  most  abundant  on  the  solid  surface  of 
the  globe,  are  not  those  which  are  the  most  essential 
to  the  existence  of  the  living  beings  belonging  to  it. 

The  action  of  the  atmosphere  on  plants  differs 
at  different  periods  of  their  growth,  and  varies  with 
the  various  stages  of  the  developement  and  decay  of 
their  organs;  some  general  idea  of  its  influence  may 
have  been  gained  from  circumstances  already  mention- 
ed: I  shall  now  refer  to  it  more  particularly,  and  endea- 
vour to  connect  it  with  a  general  view  of  the  progress 
of  vegetation. 

If  a  healthy  seed  be  moistened  and  exposed  to 
air  at  a  temperature  not  below  45°,  it  soon  germinates; 
it  shoots  forth  a  plume  which  rises  upwards,  and  a 
radicle  which  descends. 

If  the  air  be  confined,  it  is  found  that  in  the  pro- 
cess of  germination  the  oxygene,  or  a  part  of  it  is  ab- 
sorbed. The  azote  remains  unaltered;  no  carbonic 
acid  is  taken  away  from  the  air,  on  the  contrary  some 
is  added. 

Seeds  are  incapable  of  germinating,  except  when 
oxygene  is  present.     In  the  exhausted  receiver  of  the 


C         190         ] 

aV-piirtip,  in  pure  azote,  in  pure  carbonic  acid,  when 
moistened  they  swell,  but  do  not  vegetate;  and  if  kept 
in  these  gasses  lose  their  living  powers,  and  undergo 
putrefaction. 

If  a  seed  be  examined  before  germination,  it  will 
be  found  more  or  less  insipid,  at  least  not  sweet;  but 
after  germination  it  is  always  sweet.  Its  coagulated 
mucilage,  or  starch,  is  converted  into  sugar  in  the  pro- 
cess; a  substance  difficult  of  solution  is  changed  into 
one  easily  soluble;  and  the  sugar  carried  through  the 
cells  or  vessels  of  the  cotyledons,  is  the  nourishment 
of  the  infant  plant,  it  is  easy  to  understand  the  nature 
of  the  change,  by  referring  to  the  facts  mentioned  in 
the  third  Lecture;  and  the  production  of  carbonic 
acid  renders  probable  the  idea,  that  the  principal  che- 
mical difference  between  sugar  and  mucilage  depends 
upon  a  slight  difference  in  the  proportions  of  their  car- 
bon. 

The  absorption  af  oxygene  by  the  seed  in  germin- 
ation, has  been  compared  to  its  absorption  in  produ- 
cing the  evolution  of  foetal  life  in  the  egg;  but  this  an- 
alogy is  only  remote.  All  animals,  from  the  most  to 
the  least  perfect  classes,  require  a  supply  of  oxygene.* 


•  The  impregnated  eggs  of  Insects,  and  even  tiches,  do  not  produce  young  ones, 
unless  they  are  supplied  with  air,  that  is,  unless  the  foetus  can  rehire.  I  have 
found  that  the  eggs  of  moths  did  not  produce  larvce  when  ■confined  in  pure  carbonic 
acid;  and  when  they  were  exposed  in  common  air,  the  oxygene  partly  disappeared/ 
and  carbonic  acid  was  formed.  The  fish  in  the  egg  or  the  spawn,  gains  its  oxygene 
from  the  air  dissolved  in  water;  and  those  fishes  that  spawn  in  spi-ing  and  surrimef 
in  still  water,  such  aS"  the  pike,  carp,  perch,  and  bream,  deposit  their  eggs  upon 
subaquatic  vegetables,  the  leaves  of  which,  in  performing  their  healthy  functions, 
snpply  oxygene  to  the  v/ater.     The  fish  that  spawn  in  winter  such  as  the  saloieuiL 


[         191         1 

From  the  moment  the  heart  begins  to  pulsate  till  it 
ceases  to  beat,  the  aeration  of  the  blood  is  constant, 
and  the  function  of  respiration  invariable;  carbonic 
acid  is  given  off  in  the  process,  but  the  chemical 
change  produced  in  the  blood  is  unknown;  nor  is  there 
any  reason  to  suppose  the  formation  of  any  substance 
similar  to  sugar.  In  th6  production  of  a  plant  from  a 
seed,  some  reservoir  of  nourishment  is  needed  before 
the  root  can  supply  sap;  and  this  reservoir  is  the  coty- 
ledon in  which  it  is  stored  up  in  an  insoluble  form,  and 
protected  if  necessary  during  the  winter,  and  rendered 
soluble  by  agents  which  are  constantly  present  on  the  ^ 
surface.  The  change  of  starch  into  sugar,  connected 
with  the  absorption  of  oxygene,  may  be  rather  com- 
pared to  a  process  of  fermentation  than  to  that  of  re- 
spiration; it  is  a  change  effected  upon  unorganized 
matter,  and  can  be  artificially  imitated;  and  in  most  of 
the  chemical  changes  that  occur  when  vegetable  com- 
pounds are  exposed  to  air,  oxygene  is  absorbed,  and 
carbonic  acid  formed  or  evolved. 

It  is  evident,  that  in  all  cases  of  tillage  the  seeds 
should  be  sown  so  as  to  be  fully  exposed  to  the  influ- 
ence of  the  air.     And  one  cause  of  the  unproductive- 
ness of  cold  clayey  adhesive  soils  is,  that  the  seed  is 
,  coated  with  matter  impermeable  to  air. 


and  trout,  seek  spots  where  there  is  a  constant  supply  of  fresh  water,  as  near  the 
sources  of  streams  as  possible,  and  in  the  most  rapid  currents  where  all  stagnation 
is  prevented,  and  where  the  water  is  saturated  with  air,  to  which  it  has  Been  ex.- 
posed  during  its  deposition  from  cloudr;.  It  is  the  instinct  leading  these  fish  to 
seek  a  supply  of  air  for  their  eggs  which  carries  thenri  fvom  seas,  or  iafkes  into  the 
mountain  country;  which  induces  them  to  move  against  the  atrcanj,  and  to  en«?ero 
our  to  overleap  weirs,  nvilldams,  and  cataract?. 


[         192         3 

In  sandy  soils  the  earth  is  always  sufficiently  pen- 
etrable by  the  atmosphere;  but  in  clayey  soils  there 
can  scarcely  be  too  great  a  mechanical  division  of 
parts  in  the  process  of  tillage.  Any  seed  not  fully 
supplied  with  air,  always  produces  a  weak  and  diseas- 
ed plant. 

The  process  of  malting,  which  has  been  already 
referred  to,  is  merely  a  process  in  which  germination 
is  artificially  produced;  and  in  which  the  starch  of  the 
cotyledon  is  changed  into  sugar;  which  sugar  is  after- 
wards, by  fermination,  converted  into  spirit. 

It  is  very  evident  from  the  chemical  principles  of 
germination,  that  the  process  of  malting  should  be 
carried  on  no  farther  than  to  produce  the  sprouting  of 
the  radicle,  and  should  be  checked  as  soon  as  this  has 
made  its  distinct  appearance.  If  it  is  pushed  to  such 
a  degree  as  to  occasion  the  perfect  development  of  the 
radicle  and  the  plume,  a  considerable  quantity  of  sac- 
charine matter  will  have  been  consumed  in  producing 
their  expansion,  and  there  will  be  less  spirit  formed  in 
fermentation,  or  produced  in  distillation. 

As  this  circumstance  is  of  some  importance,  I 
made  in  October  1 806,  an  experiment  relating  to  it. 
I  ascertained  by  the  action  of  alcohol,  the  relative  pro- 
portions of  saccharine  matter  in  two  equal  quantities 
of  the  same  barley;  in  one  of  which  the  germination 
had  proceeded  so  far  as  to  occasion  protrusion  of  the 
radicle  to  nearly  a  quarter  of  an  inch  beyond  the  graiu 
in  most  of  the  specimens,  and  in  the  other  of  which  it 
had  been  checked  before  the  radicle  was  a  line  in 
length;  the  quantity  of  sugar  afforded  by  the  last  was 
to  that  in  the  first  nearly  as  six  to  five. 


'         .  [  193  ] 

The  saccharine  matter  in  the  cotyledons  at  the 
time  of  their  change  into  seed-leaves,  renders  them  ex- 
ceedingly liable  to  the  attacks  of  insects  :  this  princi- 
ple is  at  once  a  nourishment  of  plants  and  animals, 
and  the  greatest  ravages  are  committed  upon  crops  in 
the  first  stage  of  their  growth. 

The  turnip  fly,  an  insect  of  the  colyoptera  genus, 
fixes  itself  upon  the  seed-leaves  of  the  turnip  at  the 
time  that  they  are  beginning  to  perform  their  func- 
tions ;  and  when  the  rough  leaves  of  the  plume  are 
thrown  forth,  it  is  incapable  of  injuring  the  plant  to 
any  extent. 

Several  methods  have  been  proposed  for  destroy- 
ing the  turnip  fly,  or  for  preventing  it  from  injuring 
the  crop.  It  has  been  proposed  to  sow  radish-seed 
with  the  turnip-seed,  on  the  idea  that  the  insect  is  fon- 
der of  the  seed-leaves  of  the  radish  than  those  of  the 
turnip  ;  it  is  said  that  this  plan  has  not  been  success- 
ful, and  that  the  fly  feeds  indiscriminately  on  both. 

There  are  several  chemical  menstrua  which  ren- 
der the  process  of  germination  much  more  rapid, 
when  the  seeds  have  been  steeped  in  them.  As  in 
these  cases  the  seed-leaves  are  quickly  produced,  and 
more  speedily  perform  their  functions,  I  proposed  it 
as  a  subject  of  experiment  to  examine  whether  such 
menstrua  might  not  be  useful  in  raising  the  turnip 
more  speedily  to  that  state  in  which  it  would  be  se- 
cure from  the  fly  ;  but  the  result  proved  that  the  prac- 
tice was  inadmissible  ;  for  seeds  so  treated,  though 
they  germinated  much  quicker,  did  not  produce 
healthy  plants,  and  often  died  soon  after  spi'outing.    : 

c2 


C         194         ] 

I  Steeped  radish  seeds  In  September  1807,  for  12 
hours,  in  a  solution  of  chlorine,  and  similar  seeds  in 
very  diluted  nitric  acid,  in  Vvery  diluted  sulphuric  acid, 
in  weak  solution  of  oxysulphate  of  iron,  and  some  hi 
common  water.  The  seeds  in  solutions  of  chlorine 
and  oxysulphate  of  iron,  threw  out  the  germ  in  two 
days  ;  those  in  nitric  acid  in  three  days,  in  sulphuric 
acid  in  five,  and  those  in  water  in  seven  days.  But 
in  the  cases  of  premature  germination,  though  the 
plume  was  very  vigorous  for  a  short  time,  yet  it  be- 
came at  the  end  of  a  fortnight  weak  and  sickly  ;  and 
at  that  period  less  vigorous  in  its  growth  than  the 
sprouts  which  had  been  naturally  developed,  so  that 
there  can  be  scarcely  any  useful  application  of  these 
experiments.  Too  rapid  growth  and  premature  de- 
cay seem  invariably  connected  in  organized  struc- 
tures ;  and  it  is  only  by  following  the  slow  operations 
of  natural  causes,  that  we  are  capable  of  making  im- 
provements. 

There  is  a  number  of  chemical  substances  which 
are  very  offensive  and  even  deadly  to  insects,  which 
do  not  injure,  and  some  of  which  even  assist  vegeta- 
tion. Several  of  these  mixtures  have  been  tried  with 
various  success ;  a  mixture  of  sulphur  and  lime, 
which  is  very  destructive  to  slugs,  does  not  prevent 
the  ravages  of  the  fly  on  the  young  turnip  crop.  His 
Grace  the  Duke  of  Bedford,  at  my  suggestion,  was 
so  good  as  to  order  the  experiment  to  be  tried  on  a 
considerable  scale  at  Woburn  farm :  the  mixture  of 
lime  and  sulphur  was  strewed  over  one  part  of  a  field 
sown  with  turnips  5  nothing  was  applied  to  the  other 


[         195^       ] 

part,  but  both  were  attacked  nearly  in  the  same  man- 
ner by  the  fly. 

Mixtures  of  soot  and  quicklime,  and  urine  and 
quicklime,  will  probably  be  more  efficacious.  The 
volatile  alkali  given  off  by  these  mixtures  is  offensive 
to  insects  ;  and  they  afford  nourishment  to  the  plant. 
Mr.  T.  A.  Knight*  informs  me,  that  he  has  tried 
the  method  by  ammoniacal  fumes  with  success  ;  but 
more  extensive  trials  are  necessary  to  establish  its  gen- 


•  Mr.  Knight  has  been  so  good  as  to  furnish  me  with  the  following  note  on 
this  subject. 

"  The  experiment  which  I  tried  the  year  before  last,  and  last  year,  to  pre- 
serve turnips  from  the  fly,  has  not  been  sufficiently  often  repeated  to  enable  me  t» 
speak  with  any  degree  of  decision  ;  and  last  year  all  my  turnips  succeeded  per- 
fectly well.  In  consequence  of  your  suggestion,  when  I  had  the  pleasui-e  to  meet 
Tou  some  years  ago  at  Holkham,  that  lime  slaked  with  urine  might  possibly  be 
found  to  kill,  or  drive  off,  the  insects  from  a  turnip  crop,  I  tried  that  preparation 
ill  mixture  with  three  parts  of  soot,  which  was  put  into  a  small  barrel,  with  gim- 
blet  holes  round  it,  to  permit  a  certain  quantity  of  the,  composition,  about  four 
bushels  to  an  acre,  to  pass  out,  and  to  fall  into  the  drills  with  the  turnip  seeds. 
Whether  it  was  by  affording  highly  stimulating  food  to  the  plant,  or  giving  some 
iUvour  which  the  flies  did  not  like,  I  cannot  tell  ;  but  in  the  year  1811,  the  adjoin- 
ing rows  were  eaten  away,  and  those  to  which  the  composition  was  applied,  as 
above  described,  were  scarcely  at  all  touched.  It  is  my  intention  in  future  to  drill 
my  crop  in,  first,  with  the  composition  on  the  top  of  the  ridge  ;  and  then  to  sow 
at  least  a  pound  of  seed,  broad-cast,  over  the  whole  ground.  The  expense  of  this 
will  be  very  trifling,  not  more  than  2s.  per  acre  ;  and  the  horse-hoe  will  instantly 
sweep  away  all  the  supernumeraries  between  the  rows,  should  those  escape  the 
flies,  to  which  however  they  will  be  chiefly  attracted  ;  because  it  will  always  be 
found  that  those  insects  prefer  turnips  growing  in  poor,  to  those  in  rich  ground. 
One  advantage  seems  to  be  the  acceleration  given  to  the  growth  of  the  plants, 
by  the  highly  stimulative  effects  of  the  food  they  instantly  receive  as  soon  as  their 
growth  commences,  and  long  before  their  radicles  have  reached  the  dung<  The" 
directions  abcive  given  apply  only  to  turnips  sewed  upon  ridges,  with  the  manure 
immediately  under  them  ;  and  I  am  quite  certain,  that  in  all  soils  turnips  should 
be  thus  cultivated.  The  close  vicinity  of  the  manure,  and  the  consequent  short 
time  required  to  carry  the  food  into  the  leaf,  and  return  the  organizable  matter  to 
the  roots,  are,  in  my  hypothesis,  points  of  vast  importance  ;  and  the  results  in 
practice  are  correspondent.** 


C         196        ] 

eral  efficacy.     It  may,  however,  be  safely  adopted,  for    *^ 
if  it  should  fail  in  destroying  the  fly,  it  will  at  least  be* 
an  useful  manure  to  the  land. 

After  the  roots  and  leaves  of  the  infant  plant  are 
formed,  the  cells  and  tubes  throughout  its  structure 
become  filled  with  fluid,  which  is  usually  supplied  from 
the  soil,  and  the  function  of  nourishment  is  perform- 
ed by  the  action  of  its  organs  upon  the  external  ele- 
ments. The  constituent  parts  of  the  air  are  subser- 
vient to  this  process ;  but,  as  it  might  be  expected, 
they  act  differently  under  different  circumstances. 

When  a  growing  plant,  the  roots  of  which  are  sup- 
plied with  proper  nourishment,  is  exposed  in  the  pre- 
sence of  solar  light  to  a  given  quantity  of  atmospheri- 
cal air,  containing  its  due  proportion  of  carbonic  acid, 
the  carbonic  acid  after  a  certain  time  is  destroyed,  and 
a  certain  quantity  of  oxygene  is  found  in  its  place.  If 
new  quantities  of  carbonic  acid  gas  be  supplied,  the 
same  result  occurs  ;  so  that  carbon  is  added  to  plants 
from  the  air  by  the  process  of  vegetation  in  sunshine  ; 
^nd  oxygene  is  added  to  the  atmosphere. 

This  circumstance  is  proved  by  a  number  of  ex- 
periments made  by  Drs.  Priestley,  Ingenhousz  and 
Woodhouse,  and  M.  T.  de  Saussure ;  many  of  which 
I  have  repeated  with  similar  results.  -  The  absorption 
of  carbonic  acid  gas,  and  the  production  of  oxygene 
are  performed  by  the  leaf ;  and  leaves  recently  separ- 
ated from  the  tree  effect  the  change,  when  confined  in 
portions  of  air  containing  carbonic  acid  ;  and  absorb 
carbonic  acid  and  produce  oxygene,  even  when  im- 
mersed in  water  holding  carbonic  acid  in  solution. 


C         197        3 

The  carbonic  acid  is  probably  absorbed  by  the 
fluids  in  the  cells  of  the  green  or  parenchymatous  part 
of  the  leaf;  and  it  is  from  this  part  that  oxygene  gas 
is  produced  during  the  presence  of  light.  M.  Senne- 
bier  found  that  the  leaf,  from  which  the  epidermis  was 
stripped  off,  continued  to  produce  oxygene  when 
placed  in  water,  containing  carbonic  acid  gas,  and  the 
globules  of  air  rose  from  the  denuded  parenchyma; 
and  it  is  shewn  both  from  the  experiments  of  Senne- 
bier  and  Woodhouse,  that  the  leaves  most  abundant 
in  parenchymatous  parts  produce  most  oxygene  in 
water  impregnated  with  carbonic  acid. 

Some  few  plants  *  will  vegetate  in  an  artificial  at- 
mosphere, consisting  principally  of  carbonic  acid,  and 
many  will  grow  for  some  time  in  air,  containing  from 
one-half  to  one-third;  but  they  are  not  so  '^calthy  as 
when  supplied  with  smaller  quantities  of  this  elastic 

substance. 

Plants  exposed  to  light  have  been  found  to  pro- 
duce oxygene  gas  in  an  elastic  medium  and  in  wa- 
ter, containing  no  carbonic  acid  gas;  but  in  quantities 
much  smaller  than  when  carbonic  acid  gas  was  pre- 
sent. 

In  the  dark  no  oxygene  gas  is  produced  by 
plants,  whatever  be  the  elastic  medium  to  which  they 
are  exposed;  and  no  carbonic  acid  absorbed.  In  most 
cases,  on  the  contrary,  oxygene  gas,  if  it  be  present,  is 
absorbed,  and  carbonic  acid  gas  is  produced. 


*  I  foand  the  Arenaria  tenuifoUa  to  produce  oxygene  ia  carbonic  acid,  which 
wa?  nearly  pure. 


C         198         3 

In  the  changes  that  take  place  in  the  composition 
of  the  organized  parts,  it  is  probable  that  saccharine 
compounds  are  principally  formed  during  the  absence 
of  light;  gum,  woody  fibre,  oils,  and  resins  during 
its  presence;  and  the  evolution  of  carbonic  acid  gas,  or 
its  formation  during  the  night,  may  be  necessary  to 
give,  greater  solubility  to  certain  compounds  in  the 
plant.  I  once  suspected  that  all  the  carbonic  acid  gas 
produced  by  plants  in  the  night,  or  in  shade,  might  be 
owing  to  the  decay  of  some  part  of  the  leaf,  or  epider- 
mis; but  the  recent  experiments  of  Mr.  D.  Ellis,  are 
opposed  to  this  idea;  and  I  found  that  a  perfectly 
healthy  plant  of  celery,  placed  in  a  given  portion  of  air 
for  a  few  hours'only,  occasioned  a  production  of  car- 
bonic acid  gas,  and  an  absorption  of  oxygene. 

Some  persons  have  supposed  that  plants  exposed 
in  the  free  atmosphere  to  the  vicissitudes  of  sunshine 
and  shade,  light  and  darkness,  consume  more  oxy- 
gene than  they  produce,  and  that  their  permanent  agen- 
cy upon  air  is  similar  to  that  of  animals;  and  this  opin- 
ion is  espoused  by  the  writer  on  the  subject  I  have 
just  quoted,  in  his  ingenious  researches  on  vegetation. 
But  all  the  experiments  brought  forwards  in  favour  of 
this  idea,  and  particularly  his  experiments,  have  been 
made  under  circumstances  unfavourable  to  accuracy 
of  result.  The  plants  have  been  confined  and  suppli- 
ed with  food  in  an  unnatural  manner;  and  the  influ- 
ence of  light  upon  them  has  been  very  much  dimin- 
ished by  the  nature  of  the  media  through  which  it  pas- 
sed. Plants  confined  in  limited  portions  of  atmos- 
pheric air  soon  become  diseased;  their  leaves  decay. 


r     1^^     ] 

and  by  their  decomposiiion  they  rapidly  destroy  the 
oxygene  of  the  air.  In  some  of  the  early  experiments 
of  Dr.  Priestley  before  he  was  acquainted  with  the 
agency  of  light  upon  leaves,  air  that  had  supported 
combustion  and  respiration,  was  found  purified  by  the 
growth  of  plants  when  they  were  exposed  in  it  for  suc- 
cessive days  and  nights  ;  and  his  experiments  are  the 
more  unexceptionable,  as  the  plants,  in  many  of  them, 
grew  in  their  natural  states  ;  and  shoots,  or  branches 
from  them,  only  where  introduced  through  water  into 
the  confined  atmosphere. 

I  have  made  some  few  researches  on  this  subject, 
and  I  shall  describe  their  results.  On  the  12th  of 
July,  1 800,  I  place  a  turf  four  inches  square,  clothed 
with  grass,  principally  meadow  fox-tail,  and  white 
clover,  in  a  porcelain  dish,  standing  in  a  shallow  tray 
filled  with  water ;  I  then  covered  it  with  a  jar  of  flint 
glass,  containing  380  cubical  inches  of  common  air  in 
its  natural  state.  It  was  exposed  in  a  garden,  so  as 
to  be  liable  to  the  same  changes  with  respect  to  light 
as  in  the  common  air.  On  the  20th  of  July  the  results 
were  examined.  There  was  an  increase  of  the  volume 
of  the  gas,  amounting  to  fifteen  cubical  inches ;  but  the 
temperature  had  changed  from  64°  to  71°;  and  the 
pressure  of  the  atmosphere,  which  on  the  12th  had 
been  equal  to  the  support  of  30.1  inches  of  mercury, 
was  now  equal  to  that  of  SO. 2.  Some  of  the  leaves  of 
the  white  clover,  and  of  the  fox-tail  were  yellow,  and 
the  whole  appearance  of  the  grass  less  healthy  than 
when  it  was  first  introduced.  A  cubical  inch  of  the 
gas,  a^tated  in  lime-water,  gave  a  slight  turbidness  to 


C       '^00       ] 

the  water  j  and  the  absorption  was  not  quite  rh  of  its 
volume.  10  parts  .of  the  residual  gas  exposed  to  a 
solution  of  green  sulphate  of  iron,  impregnated  with 
nitrous  gas,  a  substance  which  rapidly  absorbs  oxygene 
from  air,  occasioned  a  diminution  to  80  parts.  00 
parts  of  the  air  of  the  garden  occasioned  a  diminution 
to  7^  parts. 

If  the  results  of  this  experiment  be  calculated 
upon,  it  will  appear  that  the  air  had  been  slightly 
deteriorated  by  the  acdon  of  the  grasses.  But  the 
weather  was  unusually  cloudy  during  the  progress  of 
the  experiment ;  the  plants  had  not  been  supplied  in  a 
natural  manner  with  carbonic  acid  gas  ;  and  the  quan- 
tity formed  during  the  night,  and  by  the  action  of  the 
laded  leaves,  must  have  been  partly  dissolved  by  the 
water  ;  and  that  this  was  actually  the  cast:',  I  proved 
by  pouring  lime-water  into  the  water,  when  an  imme- 
diate precipitation  was  occasioned.  The  increase  of 
azote  I  am  inchned  to  attribute  to  common  air  disen- 
gaged from  the  water. 

The  following  experiment  I  consider  as  conduct- 
ed under  circumstances  more  analogous  to  those  exis- 
ting in  nature.  A  turf  four  inches  square,  from  an 
irrigated  meadow,  clothed  with  common  meadow 
grass,  meadow  fox- tail  grass,  and  vernal  meadow  grass, 
was  placed  in  a  porcelain  dish,  which  swam  onthe  sur- 
face of  water  impregnated  with  carbonic  acid  gas.  A 
vessel  of  thin  flint  glass,  of  the  capacity  of  230  cubi- 
cal inches,  having  a  funnel  furnished  with  stop-cock 
inserted  in  the  top,  was  made  to  cover  the  grass  ;  and 
the  apparatus  was  exposed  in  an  open  place  j  a  small 


Fiij.  11 


p.  LHH 


[  20k         J 

quantity  of  water  was  daily  supplied  to  the  grass  by 
means  of  the  stop-cock.*  Every  day  likewise  a  certain 
qu^tity  of  water  was  removed  by  a  siphon,  and  water 
staturated  with  carbonic  acid  gas  supplied  in  its  place ; 
so  that  it  may  be  presumed,  that  a  small  quantity  of 
carbonic  add  gas  was  constantly  present  in  the  re- 
ceiver. On  the  7th  of  July,  1807,  the  first  day  of 
the  experiment,  the  weather  was  cloudy  in  the  morn- 
ing,-but  fine  in  the  afternoon  ;  the  thermometer  at 
C7,  the  barometer  30.2  :  towards  the  evening  of  this 
day  a  slight  increase  of  the  gas  was  perceived,  the  next 
three  days  were  bright ;  but  in  the  morning  of  the 
1 1  th  the  sky  was  clouded ;  a  considerable  increase  of 
the  volume  of  the  gas  was  now  observed  :  the  1 2th 
was  cloudy,  with  gleams  of  sunshine  ;  there  was  still 
an  increase,  but  less  than  in  the  bright  days  ;  the  13th 
was  bright.  About  nine  o'clock  A.M.  on  the  14th 
the  receiver  was  quite  full ;  and  considering  the  ori- 
ginal quantity  in  the  jar,  it  must  have  been  increased 
by  at  least  30  cubical  inches  of  elastic  fluid  :  at  times 
during  this  day  globules  of  gas  escaped.  At  ten  on 
the  morning  of  the  15th,  I  examined  a  portion  of  the 
gass  ;  it  contained  less  than  _*_  of  carbonic  acid  gas  : 
100  parts  of  it  exposed  to  the  impregnated  solution 
left  only  75  parts  ;  so  that  the  air  was  four  per  cent, 
purer  than  the  air  of  the  atmosphere. 

I  shall  detail  another  similar  experiment  made 
with  equally  decisive  results.  A  shoot  from  a  vine^ 
having  three  healthy  leaves  belonging  to  it,  attached 


See  Fig.  17. 

D 


[       ^02         3 

to  its  parent  tree,  was  bent  so  as  to  be  placed  under 
the  receiver  which  had  been  used  in  the  last  experi- 
ment ;  the  water  confining  the  common  air  was  kept  in 
the  same  manner  impregnated  with  carbonic  acid  gas  : 
the  experiment  was  carried  on  from  August  6th  till 
August  14th,  1807  ;  during  this  time,  though  the 
weather  had  been  generally  clouded,  and  there  had 
been  some  rain,  the  volume  of  elastic  fluid  continued  to 
increase.  Its  quality  was  examined  on  the  morning  of 
the  15th;  it  contained  ^'^  of  carbonic  acid  gas,  and 
100  parts  of  it  afforded  23.5  of  oxygene  gas. 

These  facts  confirm  the  popular  opinion,  that 
when  the  leaves  of  vegetables  perform  their  healthy 
functions,  they  tend  to  purify  the  atmosphere  in  the 
common  variations  of  weather,  and  changes  from  light 
to  darkness. 

In  germination,  and  at  the  time  of  the  decay  of 
the  leaf,  oxygene  must  be  absorbed ;  but  when  it  is 
considered  how  large  a  part  of  the  surface  of  the 
earth  is  clothed  with  perennial  grasses,  and  that  half 
of  the  globe  is  always  exposed  to  the  solar  light,  it  ap- 
pears by  far  the  most  probable  opinion,  that  more 
oxygene  is  produced  than  consumed  during  the  pro- 
cess of  vegetation ;  and  that  it  is  this  circumstance 
which  is  the  principal  cause  of  the  uniformity  of  the 
constitution  of  the  atmosphere. 

Animals  produce  no  oxygene  gas  during  the  ex- 
ercise of  any  of  their  functions  and  they  are  constantly 
consuming  it ;  but  the  extent  of  the  animal,  compar- 
ed to  that  of  the  vegetable,  kingdom  is  very  small ; 
and  the  quantity  of  carbonic  acid  gas    produced 


C  203  3      ^ 

in  respiration,  and  in  various  processes  of  com- 
bustion and  fermentation,  bears  a  proportion  ex- 
tremely  minute  to  the  whole  volume  of  the  atmos- 
phere :  if  every  plant  during  the  progress  of  its  life 
makes  a  very  small  addition  of  oxygene  to  the  air,  and 
occasions  a  very  small  consumption  of  carbonic  acid, 
the  effect  may  be  conceived  adequate  to  the  wants  of 
nature. 

It  may  occur  as  an  objection  to  these  views,  that 
if  the  leaves,  of  plants  purify  the  atmosphere,  towards 
the  end  of  autumn,  and  through  the  winter,  and  early 
spring,  the  air  in  our  climates  must  become  impure, 
the  oxygene  in  it  diminish,  and  the  carbonic  acid  gas 
increase,  which  is  not  the  case ;  but  there  is  a  very 
satisfactory  answer  to  this  objection.  The  different 
parts  of  the  atmosphere  are  constantly  mixed  together 
by  winds,  which  when  they  are  strong,  move  at  the 
rate  of  from  60  to  100  miles  in  an  hour.  In  our  win- 
ter, the  south-west  gales  convey  air^  which  has  been, 
purified  by  the  vast  forests  and  savannas  of  South 
America,  and  which,  passing  over  the  ocean,  arrives 
in  an  uncontaminated  state.  The  storms  and  tempests 
which  often  occur  at  the  beginning,  and  towards  the 
middle  of  our  winter,  and  which  generally  blow 
from  the  same  quarter  of  the  globe,  have  a  salutary 
influence.  By  constant  agitation  and  motion,  the 
equilibrium  of  the  constituent  parts  of  the  atmosphere 
is  preserved  ;  it  is  fitted  for  the  purposes  of  life ;  and 
those  events,  which  the  superstitious  formerly  refer- 
red to  the  wrath  of  heaven,  or  the  agency  of  evil 
spirits,  and  in  which  they  saw  only  disorder  and  con- 


n  204  J 

fusion,  are  demonstrated  by  science,  to  be  ininistra- 
tions  of  divine  intelligence,  and  connected  with  the  or- 
der and  harmony  of  our  system. 

I  have  reasoned,  in  a  former  part  of  this  Lecture, 
against  the  close  analogy  which  some  persons  have  as- 
sumed between  the  absorption  of  oxygene  and  the  for- 
mation of  carbonic  acid  gas  in  germination,  and  in  the 
respiration  ot  the  foetus.  Similar  arguments  will  ap- 
ply against  the  pursuit  of  this  analogy  between  the 
functions  of  the  leaves  of  the  adult  plant,  and  those  of 
the  lungs  of  the  adult  animal.  Plants  grow  vigorous- 
ly only  when  supplied  with  light ;  and  most  species 
die  if  deprived  of  it.  It  cannot  be  supposed  that  the 
production  of  oxygene  from  the  leaf,  which  is  known 
to  be  connected  with  its  natural  colour,  is  the  exertion 
of  a  diseased  function,  or  that  it  can  acquire  carbon  in 
the  day-time,  when  it  is  in  most  vigorous  growth, 
when  the  sap  is  rising,  when  all  its  powers  of  obtain- 
ing nourishment  are  exerted  ;  merely  for  the  purpose 
of  giving  it  off  again  in  the  night,  when  its  leaves  are 
closed,  when  the  motion  of  the  sap  is  imperfect,  and 
wheii  it  is  in  a  state  approaching  to  that  of  quiescence. 
Many  plants  that  grow  upon  rocks,  or  soils,  contain- 
ing no  carbonic  matter,  can  only  be  supposed  to  ac- 
quire their  charcoal  from  the  carbonic  acid  gas  in  the 
atmosphere  ;  and  the  leaf  may  be  considered  at  the 
same  time  as  an  organ  of  absorption,  and  an  organ 
in  which  the  sap  may  undergo  different  chemical 
changes. 

When  pure  water  only  is  absorbed  by  the  roots 
of  plants,  the  fluid,  in  passing  into  the  leaves,  will 


t 

probably  have  greater  power  to  absorb  carbonic  acid 
from  the  atmosphere,  when  the  water  is  saturated  with 
carbonic  acid  gas,  some  of  this  substance,  even  in  the 
sunshine,  may  be  given  off  by  the  leaves;  but  a  part  of* 
it  likewise  will  be  always  decomposed,  which  has  been 
proved  by  the  experiments  of  M.  Sennebier. 

When  the  fluid  taken  up  by  the  roots  of  plants 
contains  much  carbonaceous  matter,  it  is  probable 
that  plants  may  give  off  carbonic  acid  from  their  leaves, 
even  in  the  sunshine.  In  short,  the  function  of  the 
leaf  must  vary  according  to  the  composition  of  the  sap 
passing  through  it.  When  sugar  is  to  be  produced, 
as  in  early  spring  at  the  time  of  the  development  of 
buds  and  flowers,  it  is  probable  that  less  oxygene  will 
be  gw^n  off,  than  at  the  time  of  the  ripening  of  the 
seed,  when  starch,  or  gums,  or  soils,  ai^  formed;  and 
the  process  of  ripening  the  seed  usually  takes  place 
when  the  agency  of  the  solar  light  is  most  intense. 
Whentheacid  juices  of  fruits  become  saccharine  in  the 
natural  process  of  vegetation,  more  oxygene,  there 
is  every  reason  to  believe,  must  be  given  off,  or  new- 
ly combined,  than  at  other  times;  for,  as  it  was  shewn 
in  the  third  Lecture,  all  the  vegetable  acids  contain 
more  oxygene  than  sugar.  It  appears  probable,  that 
in  some  cases,  in  which  oily  and  resinous  bodies  are 
formed  in  vegetation,  water  may  be  decomposed:  its 
oxygene  set  free,  and  its  hydrogene  absorbed. 

I  have  already  mentioned,  that  some  plants  pro- 
duce oxygene  in  pure  water;  Dr.  Ingenhousz  foiHid 
this  to  be  the  case  with  species  of  the  confervse;  I 
have  tried  the  leaves  of  many  plaats,  particularly  those 


C       2oej       ], 

that  produce  volatile  oils.  When  such  leaves  are  ex- 
posed in  water  saturated  with  oxygene  gas,  oxygene 
is  given  off  in  the  solar  light;  but  the  quantity  is  very 
small  and  always  limited;  nor  have  I  been  able  to  as- 
certain with  certainty,  whether  the  vegetative  powers 
of  the  leaf  were  concerned  in  the  operation,  though  it 
seems  probable.  I  obtained  a  considerable  quantity  of 
oxygene  in  an  experiment  made  fifteen  years  ago, 
in  which  vine  leaves  were  exposed  to  pure  water;  but 
on  repeating  the  trial  often  since,  the  quantities  have 
always  been  very  much  smaller;  I  am  ignorant  whe- 
ther this  difference  is  owing  to  the  peculiar  state  of  the 
leaves,  or  to  some  confervas  which  might  have  adher- 
ed to  the  vessel,  or  to  other  sources  of  fallacy. 

The  most  important  and  most  common  products  of 
vegetables,  mucilage,  starch,  sugar,  and  woody  fibre, 
are  composed  of  water,  or  the  elements  of  water  in 
their  due  proportion,  and  charcoal;  and  these,  or  some 
of  them,  exist  in  all  plants;  and  the  decomposition  of 
carbonic  acid,  and  the  combination  of  water  in  vege- 
table structures,  are  processes  which  must  occur  al- 
most universally. 

When  glutenous  and  albuminous  substances  ex- 
ist in  plants,  the  azote  they  contain  may  be  suspected 
to  be  derived  from  the  atmosphere;  but  no  experi- 
ments have  been  made  which  prove  this;  they  might 
easily  be  instituted  upon  mushrooms  and  fungusses. 

In  cases  in  which  buds  are  formed,  or  shoots 
thrown  forth  from  roots,  oxygene  appears  to  be  urn- 
formly  absorbed,  as  in  the  germination  of  seeds.  I 
exposed  a  small  potatoe  moistened  with  common  wa- 


[         207 


<( 


ter  to  24  cubical  inches  of  atmospherical  air,  at  a  tem- 
perature of  59°.  It  began  to  throw  forth  a  shoot  on 
the  third  day;  when  it  was  a  half  an  inch  long  I  ex- 
amined the  air;  nearly  a  cubical  inch  of  oxygene  was 
absorbed,  and  about  three-fourths  of  a  cubical  inch  of 
carbonic  acid  formed.  The  juices  in  the  shoot  separ-  ^^ 
ated  from  the  potatoe,  had  a  sweet  taste;  and  the  ab- 
sorption of  oxygene,  and  the  production  of  carbonic 
acid,  were  probably  connected  with  the  conversion  of 
a  portion  of  starch  into  sugar.  When  potatoes  that 
h,ave  been  frozen  are  thawed,  they  become  sweet;  pro- 
bably  oxygene  is  absorbed  in  this  process;  if  so,  the 
change  may  be  prevented  by  thawing  them  out  of  the 
contact  of  air,  under  water,  for  instance,  that  has 
been  recently  boiled. 

In  the  tillering  of  corn  that  is,  the  production  of 
new  stalks  round  the  original  plume,  there  is  every  rea- 
son to  believe  that  oxygene  must  be  absorbed;  for  the 
stalk  at  which  the  tillering  takes  place,  always  con- 
t^ns  sugar,  and  the  shoots  arise  from  a  part  derived  of- 
light.  The  drill  husbandry  favours  this  process;  for 
loose  earth  is  thrown  by  hoeing  round  the  stalks;  they 
are  preserved  from  light,  an4  yet  supplied  with  oxy- 
gene. I  have  counted  from  forty  to  one  hundred  and 
twenty  stalks;  produced  from  a  grain  of  wheat,  in  a 
moderately  good  crop  of  drilled  wheat.  And  we  are 
informed  by  Sir  Kenelm  Digby  in  1660,  that  there  was  , 
in  the  possession  of  the  Fathers  of  the  Christian  Doc- 
trine at  Paris,  a  plant  of  barley  which  they,  at  that  time, 
kept  by  them  as  a  curiosity,  and  which  consisted  of  249 
stalks  springing  from  one  root,  or  grain;  and  in  which 
they  counted  above  18,000  grains,  or  seeds  of  barley. 


[  203  3 

The  great  increase  which  takes  place  in  the  trans- 
plantation  of  wheat,  depends  upon  the  circumstanccj 
that  each  layer  thrown  out  in  tillering  may  be  remov- 
ed, and  treated  as  a  distinct  plant.  In  the  Philosophi- 
cal Transactions,  Vol.  LVIII,  p.  203,  the  following 
statement  may  be  found :  Mr.  C.  Miller,  of  Cam- 
bridge, sowed  some  wheat  on  the  2d  of  June,  1 766  ; 
and  on  the  8th  of  August,  a  plant  was  taken  and 
separated  into  18  parts,  and  replanted;  these  plants 
were  again  taken  up,  and  divided  in  the  months  of 
September  and  October,  and  planted  separately  to 
stand  the  winter,  which  division  produced  67  plants. 
They  were  again  taken  up  in  March  and  April,  and 
produced  500  plants  :  the  number  of  ears  thus  form- 
ed from  one  grain  of  wheat  was  21109,  which  gave 
three  pecks  and  three  quarters  of  corn  that  weighed 
47lbs.  7ozs. ',  and  that  were  estimated  at  576840 
grains. 

It  is  evident  from  the  statements  just  given,  that  the 
change  which  takes  place  in  the  juices  of  the  leaf  by  the 
the  action  of  the  solar  light,  must  tend  to  increase  the 
proportion  of  inflammable  matter  to  their  other  con- 
stituent parts.  And  the  leaves  of  the  plants  that  grow 
in  darkness,  or  in  shady  places,  are  uniformly  pale  ; 
their  juices  are  watery  and  saccharine,  and  they  do 
not  afford  oils  or  resinous  substances.  I  shall  detail 
an  experiment  on  this  subject. 

I  tbok  an  equal  weight,  400  grains,  of  the  leaves 
of  two  plants  of  endive,  one  bright  green,  which  had 
grown  fully  exposed  to  light,  and  the  other  almost 
white,  which  had  been  secluded  from  light  by  beiftg 


i-* 


[         209         ] 

covered  with  a  box;  after  being  both  acted  upon  for 
some  time  by  boiling  water,  in  the  state  of  pulp,  the 
undissolved  matter  was  dried,  and  exposed  to  the 
action  of  warm  alcohol.  The  matter  from  the  green 
leaves  gave  it  a  tinge  of  olive;  that  from  the  pale  leaves 
did  not  alter  its  colour.  Scarcely  any  solid  matter 
was  produced  by  evaporation  of  the  alcohol  that  had 
been  digested  on  the  pale  leaves;  whereas  by  the  eva- 
poration of  that  from  the  green  leaves,  a  considerable 
residuum  was  obtained,  five  grains  of  which  were  se- 
parated from  the  vessel  in  which  the  evaporation  was 
carried  on;  they  burnt  with  flame,  and  appeared  partly 
matter  analogous  to  resin.  53  grains  of  woody  fibre 
were  obtained  from  the  green  leaves,  and  only  31 
from  the  pale  leaves. 

It  has  been  mentioned  in  the  Third  Lecture,  that 
the  sap  probably,  in  common  cases,  descends  from  the 
leaves  into  the  bark;  the  bark  is  usually  so  loose  in  its 
texture,  that  the  atmosphere  may  possible  act  upon  it 
in  the  cortical  layers;  but  the  changes  taking  place  in 
the  leaves,  appear  sufficient  to  explain  the  difference  be- 
tween the  products  obtained  from  the  bark  and  from 
the  alburnum;  the  first  of  which  contains  more  carbo- 
naceous matter  than  the  last. 

When  the  similarity  of  the  elements  of  different 
vegetable  products  is  considered,  according  to  the 
views  given  in  the  third  Lecture,  it  is  easy  to  conceive 
how  the  different  organized  parts  may  be  formed  from 
the  same  sap,  according  to  the  manner  in  which  it  is 
acted  on  by  heat,  light,  and  air.  By  the  abstraction 
ofoxygene,  the  different  inflammable  products,  fixed 

e2 


C  210   _     J 

and  volatile  oils,  resins,  camphor,  woody  fibre,  &c. 
may  be  produced  from  saccharine  or  mucilaginous 
fluids;  and  by  the  abstraction  of  carbon  and  hydro- 
gene,  starch,  sugar,  the  different  vegetable  acids  and 
substances  soluble  in  water,  may  be  formed  from  high- 
ly combustible  and  insoluble  substances.  Even  the 
limpid  volatile  oils  which  convey  the  fragrance  of  the 
flower,  consist  of  different  proportions  of  the  same 
essential  elements,  as  the  dense  woody  fibre;  and  both 
are  formed  by  different  changes  in  the  same  organs, 
from  the  same  materials,  and  at  the  same  time. 

M.  Vauquelin  has  lately  attempted  to  estimate 
the  chemical  changes  taking  place  in  vegetation,  by 
analysing  some  of  the  organized  parts  of  the  horse- 
chesnut  in  their  different  stages  of  growth.  He  found 
in  the  buds  collected,  March  7.  1812,  tanning  princi- 
ple, and  albuminous  matter  capable  of  being  obtained 
separately,  but  when  obtained,  combining  with  each 
other.  In  the  scales  surrounding  the  buds,  he  found 
the  tanning  principle,  a  little  saccharine  matter,  resin, 
and  a  fixed  oil.  In  the  leaves  fully  developed,  he  dis- 
covered the  same  principles  as  in  the  buds;  and  in  ad- 
dition, a  peculiar  green  resinous  matter.  The  petals 
of  the  flower  yielded  a  yellowish  resin,  saccharine  mat- 
ter, albuminous  matter,  and  a  little  wax:  the  stamina 
afforded  sugar,  resin,  and  tannin. 

The  young  chesnuts  examined  immediately  after 
their  formation,  afforded  a  large  quantity  of  a  matter 
which  appeared  to  be  a  combination  of  albuminous 
matter  and  tannin.  All  the  parts  of  the  plant  aff'ord- 
ed  saline  combinations  of  the  acetic  and  phosphoric 
acids. 


C  211  ] 

M.  Vauquelin  could  not  obtain  a  sufficient  quan- 
tity of  the  sap  of  the  horse-chesnut  for  examination;  a 
circumstance  much  to  be  regretted;  and  he  has  not 
stated  the  relative  quantities  of  the  different  substances 
in  the  buds,  leaves,  flowers,  and  seeds.  It  is  proba- 
ble, however,  from  his  unfinished  details,  that  the 
quantity  of  resinous  matter  is  increased  in  the  leaf,  and 
that  the  white  fibrous  pulp  of  the  chesnut  is  formed 
by  the  mutual  action  of  albuminous  and  astringent, 
matter,  which  probably  are  supplied  by  different  cells 
or  vessels.  I  have  already  mentioned^  that  the  cam- 
bium, from  which  the  new  parts  of  the  trunk  and  the 
branches  appear  to  be  formed,  probably  owes  its  pow- 
er of  consolidation  to  the  mixture  of^two  different 
kinds  of  sap;  one  of  which  flows  upwards  from  the 
roots;  and  other  of  which  probably  descends  from  the 
leaves.  I  attempted,  in  May  1804,  at  the  time  the 
cambium  was  forming  in  the  oak,  to  ascertain  the  na- 
ture of  the  action  of  the  sap  of  the  alburnum  upon  the 
juices  of  the  bark*  By  perforating  the  alburnum  m  a 
young  oak,  and  applying  an  exhausting  syringe  to  the 
aperture,  I  easily  drew  out  a  small  quantity  of  sap. 
I  could  not,  however,  in  the  same  way  obtain  sap  from 
the  bark.  I  was  obliged  to  recur  to  the  solution  of 
its  principles  in  water,  by  infusing  a  small  quantity  of 
fresh  bark  in  warm  watery  the  liquid  obtained  in  this 
way  was  highly  coloured  and  astringent;  and  produc- 
ed an  immediate  precipitate  in  the  alburnous  sap,  the 

•  Page  131.. 


C  212  ] 

taste  of  which  was  sweetish,  aud  sligtitly  astringent, 
and  which  was  colourless. 

The  increase  of  trees  and  plants  must  depend 
upon  the  quantity  of  sap  which  passes  into  the  organs 
upon  the  quality  of  this  sap;  and  on  its  modification 
by  the  principles  of  the  atmosphere.  Water,  as  it  is 
the  vehicle  of  the  nourishment  of  the  plant,  is  the  sub- 
stance principally  given  off  by  the  leaves.  Dr.  Hales 
found,  that  a  sunflower,  in  one  day  of  twelve  hours, 
transpired  by  its  leaves  one  pound  fourteen  ounces  of 
water,  all  of  which  must  have  been  imbibed  by  its 
roots. 

The  powers  which  cause  the  ascent  of  the  sap 
have  been  slightly  touched  upon  in  the  second  and 
third  Lectures.  The  roots  imbibe  fluids  from  the  soil 
by  capillary  attraction;  but  this  power  alone  is  insuffi- 
cient to  account  for  the  rapid  elevation  of  the  sap  into 
the  leaves.  This  is  fully  proved  by  the  following  fact 
detailed  by  Dr.  Hales,  Vol.  I.  of  the  Vegetable  Statics, 
page  1 14.  A  vine  branch  of  four  or  five  years  old- was 
cut  through,  and  a  glass  tube  carefully  attached  to 
it;  this  tube  was  bent  as  a  siphon,  and  filled  with  quick- 
silver; so  that  the  force  of  the  ascending  sap  could  be 
measured  by  its  effect  in  elevating  the  quicksilver.  In 
a  few  days  it  was  found,  that  the  sap  had  been  propel- 
led  forwards  with  so  much  force  as  to  raise  the  quick- 
silver to  38  inches,  which  is  a  force  considerably  su- 
perior to  that  of  the  usual  pressure  of  the  atmosphere. 
Capillary  attraction  can  only  be  exerted  by  the  sur- 
faces  of  small  vessels,  and  can  never  raise  a  fluid  into 
tubes  above  the  vessels  themselves. 


I         213         ] 

I  referred  in  the  beginning  of  the  Third  Lecture 
to  Mr.  Knight's  opinion,  that  the  contractions  and 
expansions  of  the  silver  grain  in  the  alburnum,  are 
the  most  efficient  cause  of  the  ascent  of  the  fluids  con- 
tained in  its  pores  and  vessels.  The  views  of  this  ex- 
cellent physiologist  are  rendered  extremely  probable 
by  the  facts  he  has  brought  forwards  in  support  of 
them.  Mr.  Knight  found  that  a  very  small  increase 
of  temperature  was  sufficient  to  cause  the  fibres  of  the 
silver  grain  to  separate  from  each  other,  and  that  a 
very  slight  diminution  of  heat  produced  their  contrac- 
tion. The  sap  rises  most  vigorously  in  spring  and 
autumn,  at  the  time  the  temperature  is  variable ;  and 
if  it  be  supposed,  that  in  expanding  and  contracting, 
the  elastic  fibres  of  the  silver  grain  exercise  a  pressure 
upon  the  cells  and  tubes  containing  the  fluid  absorbed 
by  the  capillary  attraction  of  the  roots,  this  fluid  must 
constantly  move  upwards  towards  the  points  where  a 
supply  is  needed. 

The  experiments  of  Montgolfier,  the  celebrated 
inventor  of  the  balloon,  have  shewn  that  water  may 
be  raised  almost  to  an  indefinite  height  by  a  very 
small  force,  provided  its  pressure  be  taken  off  by  con- 
tinued divisions  in  the  column  of  fluid.  This  princi- 
ple, there  is  great  reason  to  suppose,  must  operate  in 
assisting  the  ascent  of  the  sap  in  the  cells  and  vessels 
of  plants  which  have  no  rectilineal  communication, 
and  which  every  where  oppose  obstacles  to  the  per* 
pendicular  pressure  of  the  sap. 

The  changes  taking  place  in  the  leaves  and  buds, 
and  the  degree  of  their  power  of  transpiration,  must; 


[214         3 

be  intimately  connected  likewise  "with  the  motion  of 
the  sap  upwards.  This  is  shewn  by  several  experi- 
ments of  Dr.  Hales. 

A  branch  from  an  appple  tree  was  separated  and 
introduced  into  water,  and  connected  with  a  mercurial 
gage.  When  the  leaves  were  upon  it,  it  raised  the 
mercury  by  the  force  of  the  ascending  juices  to  four 
inches  ;  but  a  similar  branch,  from  which  the  leaves 
were  removed,  scarcely  raised  it  a  quarter  of  an  inch. 

Those  trees,  likewise,  whose  leaves  are  soft  and 
of  a  spongy  texture,  and  porous  at  their  upper  sur- 
faces, displayed  by  far  the  greatest  powers  with  regard 
to  the  elevation  of  the  sap. 

The  same  accurate  philosopher  whom  I  have  just 
quoted,  found  that  the  pear,  quince,  cherry,  walnut, 
peach,  gooseberry,  water  elder  and  sycamore,  which 
have  all  soft  and  unvarnished  leaves,  raised  the  mer- 
cury under  favourable  circumstances  from  three  to 
six  inches.  Whereas  the  elm,  oak,  chesnut,  hazel, 
sallow,  and  ash,  which  have  firmer  and  more  glossy 
leaves,  raised  the  mercury  only  from  one  to  two 
inches.  And  the  evergreens  and  trees  bearing  var- 
nished leaves,  scarcely  at  all  affected  it  5  particularly 
the  laurel  and  the  laurustinus. 

It  will  be  proper  to  mention  the  facts  which 
shew,  that  in  many  cases  fluids  descend  through  the 
bark ;  they  are  not  of  the  same  unequivocal  nature 
as  those  which  demonstrate  the  ascent  of  the  sap 
through  the  alburnum  ;  yet  many  of  them  are  satis- 
factory. 


C  215  J 

M.  Balsse  placed  branches  of  different  trees  in 
an  infusion  of  madder,  and  kept  them  there  for  a  long 
time.  He  found  in  all  cases,  that  the  wood  became 
red  before  the  bark ;  and  that  the  bark  began  to  re- 
ceive no  tinge  till  the  whole  of  the  wood  was  colour- 
ed, and  till  the  leaves  were  affected  ;  and  that  the  co- 
louring matter  first  appeared  above,  in  the  bark  im- 
mediately in  contact  with  the  leaves. 

Similar  experiments  were  made  by  M.  Bonnet, 
and  with  analogous  results,  though  not  so  perfectly 
distinct  as  those  of  M.  Baisse. 

Du  Hamel  found,  that  in  different  species  of  the 
pine  and  other  trees,  when  strips  of  bark  were  re- 
moved, the  upper  part  of  the  wound  only  emitted  fluid, 
whilst  the  lower  part  remained  dry. 

This  may  likewise  be  observed  in  the  summer 
in  fruit  trees,  when  the  bark  is  wounded,  the  alburn- 
um remaining  untouched. 

I  have  mentioned  in  the  Third  Lecture,  that  when 
new  bark  is  formed  to  supply  the  place  of  a  ring- 
that  has  been  stripped  off,  it  first  makes  its  appearance 
upon  the  upper  edge  of  the  wound,  and  spreads  slow- 
ly downwards  5  and  no  new  matter  appears  from  be- 
low rising  upwards,  if  the  experiment  has  been  care- 
fully performed.  I  say  carefully  performed  j  because,  if 
any  of  the  interior  cortical  layer  be  suffered  to  remain 
communicating  with  the  upper  edge,  new  bark  cover- 
ed with  epidermis  will  form  below  this,  and  appear  as 
if  protruded  upon  the  naked  alburnum,  and  formed 
within  the  wound  5  and  such  a  circumstance  would 
give  rise  to  erroneous  conclusions. 


^216 


hi  the  suininer  of  1804,  I  examined  some  elms 
at  Kensington.  The  bark  of  many  of  them  had  been 
very  much  injured,  and  in  some  cases  more  than  a 
square  foot  had  been  stripped  off.  In  most  of  the 
wounds  the  formation  of  the  new  cortical  layers  was 
from  above,  and  gradually  extending  downwards 
round  the  aperture  j  but  in  two  instances  there  had 
been  very  distinctly  a  formation  of  bark  towards  the 
lower  edge.  I  was  at  first  very  much  surprised  at 
this  appearance,  so  contradictory  to  the  general 
opinion  j  but  on  passing  the  point  of  a  pen-knife  along 
the  surface  of  the  alburnum,  from  below  upwards,  I 
found  that  a  part  of  the  cortical  layer,  which  was  of 
the  colour  of  the  alburnum,  had  remained  communi- 
cating with  the  upper  edge  of  the  wound,  and  that 
the  new  bark  had  formed  from  this  layer.  I  have  had 
no  opportunity  of  looldng  at  the  trees  lately ;  but  I 
doubt  not  that  the  phaenomenon  may  still  be  observ- 
ed ;  for  some  years  must  elapse  before  the  new  forma- 
tions will  be  complete. 

In  accounting  for  the  experiment  of  M.  Palisot 
de  Beauvois,  mentioned  in  the  Third  Lecture,  it  may 
be  supposed  that  the  cortical  fluid  flowed  down  the 
alburnum  upon  the  insulated  bark,  and  thus  occasion- 
ed its  increase  ;  or  it  may  be  conceived  that  the  bark 
itself  contained  sufficient  cortical  fluid  at  the  time  of 
its  separation  to  form  new  parts  by  its  action  upon  the 
alburnous  fluid. 

The  motion  of  the  sap  through  the  bark  seems 
principally  to  depend  upon  gravitation.  When  the 
watery  particles   have  been  considerably   dissipated 


C      217      2 

by  the  transpiring  functions  of  the  leaves,  and  the  mu^ 
cilaginous,  inflammable,  and  astringent  constituents, 
increased  by  the  agency  of  heat,  light,  and  air,  the 
continued  impulse  upwards  from  the  alburnum,  forces 
the  remaining  inspissated  fluid  into  the  cortical  vessels? 
which  receive  no  other  supply.  In  these,  from  its 
weight,  its  natural  tendency  must  be  to  descend; 
and  the  rapidity  of  the  descent  must  depend  upon 
the  general  consumption  of  the  fluids  of  the  bark 
in  the  living  processes  of  vegetation;  for  there  is  every 
reason  to  believe,  that  no  fluid  passes  into  the  soil 
through  the  roots;  and  it  is  impossible  to  conceive  a 
free  lateral  communication  between  the  absorbent  ves- 
sels of  the  alburnum  in  the  roots,  and  the  transport- 
ing or  carrying  vessels  of  the  bark;  for  if  such  a  com- 
munication existed,  there  is  no  reason  why  the  sap 
should  not  rise  through  the  bark  as  well  as  through 
the  alburnum;  for  the  same  physical  powers  would 
then  operate  upon  both. 

Some  authors  have  supposed  that  the  sap  rises  in 
the  alburnum,  and  descends  through  the  bark  in  con- 
sequence of  a  power  similar  to  that  which  produces  the 
circulation  of  the  blood  in  animals;  a  force  analagous 
to  the  muscular  force  in  the  sides  of  the  vessels. 

Dr.  Thomson,  in  his  System  of  Chemistry,  ha^ 
stated  a  fact  which  he  considers  as  demonstrating  the 
irritability  of  living  vegetable  systems.  When  a  stalk 
of  spurge  (Euphorbia  peplis)  is  separated  by  two  in- 
cisions fr©m  its  leaves  and  roots,  the  milky  fluid  flows 
through  both  sections.  Now,  says  the  ingenious  au- 
thor, it  is  impossible  that  this  could  happen  without 

F  2 


I  218  3 

the  living  action  of  the  vessels,  for  they  cannot  have 
been  more  than  full;  and  their  diameter  is  so  small, 
that  if  it  were  to  continue  unaltered,  the  capillary  at- 
traction would  be  more  than  sufficient  to  contain  their 
contents,  and  consequently  not  a  drop  would  flow  out. 
Since  therefore  the  liquid  escapes,  it  must  be  driven 
out  by  a  force  different  from  a  common  physical  force. 

To  this  reasoning  it  may  be  answered,  that  the 
sides  of  all  the  vessels  are  soft,  and  capable  of  collaps- 
ing by  gravitation,  as  veins  do  in  animal  systems  long 
after  they  have  lost  all  their  vitality;  which  is  an  effect 
totally  different  from  vital  or  irritable  action;  and  the 
phaenomenon  may  be  compared  to  that  of  puncturing 
a  vessel  of  elastic  gum  filled  with  fluid,  both  above  and 
below;  the  fluid  will  make  its  way  through  the  a- 
pertures,  though  in  much  larger  quantity  from  the 
lowest,  which  I  have  found  is  likewise  the  case  with  the 
Spurge. 

Dr.  Barton  has  stated,  that  plants  grow  more  vi- 
gorously in  water  in  which  a  little  camphor  has  been 
infused.  This  has  been  brought  forward  as  a  fact  in 
favour  of  the  irritability  of  the  vegetable  tubular  sys- 
tem.  It  is  said  that  camphor  can  only  be  conceived 
to  act  as  a  stimulus,  by  increasing  the  living  powers 
of  the  vessels,  and  causing  them  to  contract  with  more 
energy.  But  this  kind  of  speculation  is  very  unsatis- 
factory. Camphor,  we  know,  has  a  disagreeable  pun- 
gent taste,  and  powerful  smell;  but  physicians  are  far 
from  being  agreed  whether  it  is  a  stimulant  or  sedative, 
even  in  its  operation  upon  the  human  body.  We 
should  have  no  right  whatever,  even  supposing  the  ir- 


[         219         2 

ritabillty  of  vegetables  proved,  to  conclude,  that  be- 
cause camphor  assisted  the  growth  of  plants,  it  acted 
on  their  living  powers;  and  it  is  not  right  to  infer  the 
existence  of  a  property  proved  in  no  other  way,  from 
the  operation  of  uncertain  qualities. 

That  camphor  may  assist  the  growth  of  plants  it 
is  easy  to  conceive;  and  why  should  we  not  consider 
its  efficacy  as  similar  to  the  efficacy  of  saccharine  and 
mucilaginous  matter,  and  particularly  of  oils,  to  which 
it  is  nearly  allied  in  composition;  and  which  afford 
food  to  the  plant,  and  not  stimulus;  which  are  materi- 
als of  assimilation,  and  not  of  excitement? 

The  arguments  in  favour  of  a  contraction  similar 
to  muscular  action  have  not  then  much  weight;  and 
besides,  there  are  direct  facts  which  render  the  opinion 
highly  improbable. 

When  a  single  branch  of  a  vine  or  other  tree  is 
introduced  in  winter  into  a  hot-house,  the  trunk  and 
the  other  branches  remaining  exposed  to  the  cold  at- 
mosphere, the  sap  will  soon  begin  to  move  towards  the 
buds  in  the  heated  branch;  these  buds  will  gradually 
unfold  themselves  ajid  begin  to  transpire;  and  at  length 
open  into  leaves.  Now  if  any  peculiar  contractions  of 
the  sap  vessels  or  cells  were  necessary  for  the  ascent  of 
the  sap  in  the  vessels,  it  is  not  possible  that  the  applica- 
tion of  heat  to  a  single  branch  should  occasion  irrita- 
ble action  to  take  place  in  a  trunk  many  feet  removed 
from  it,  or  in  roots  ifixed  in  the  cold  soil:  but  allowing 
that  the  energy  of  heat  raises  the  fluid  merely  by  di- 
minishing its  gravity,  increasing  the  facility  of  capillary 
action,  and  by  producing  an  expansion  of  the  fibres 


C  220  ] 

of  the  silver  grain,  the  phaenomenon  is  in  perfect  uni- 
son with  the  views  advanced  in  the  preceeding  part 
of  this  Lecture. 

The  ilex,  or  evergreen  oak,  preserves  its  leaves 
through  the  winter,  even  when  grafted  upon  the  com- 
mon oak;  and  in  consequence  of  the  operation  of  the 
leaves  there  is  a  certain  motion  of  the  sap  from  the  oak 
towards  the  ilex,  which,  as  in  the  last  case,  seems  to 
be  inconsistent  with  the  theory  of  irritable  action. 

It  is  impossible  to  peruse  any  considerable  part 
of  the  Vegetable  Statics  of  Hales,  without  receiving  a 
deep  impression  of  the  dependence  of  the  motion  of  the 
sap  upon  common  physical  agencies.  In  the  same  tree 
this  sagacious  person  observed,  that  in  a  cold  cloudy 
morning  when  no  sap  ascended,  a  sudden  change  was 
produced  by  a  gleam  of  sunshine,  of  half  an  hour;  and  a 
vigorous  motion  of  the  fluid.  The  alteration  of  the 
wind  from  south  to  the  north  immediately  checked 
the  effect.  On  the  coming  on  of  a  cold  afternoon  after 
a  hot  day,  the  sap  that  had  been  rising  began  to  fall, 
A  warm  shower  and  a  sleet  storm  produced  opposite 
effects. 

Many  of  his  observations  likewise  shew,  that  the 
different  powers  which  act  on  the  adult  tre^,  produce 
different  effects  at  different  seasons. 

Thus  in  the  early  spring,  before  the  buds  ex- 
pand, the  variations  of  the  temperature,  and  changes 
of  the  state  of  the  atmosphere  with  regard  to  moisture 
and  dryness,  exert  their  great  effects  upon  the  expan- 
sions and  contractions  of  the  vessels;  and  then  the  tree 
is  in  what  is  called  by  gardeners  its  bleeding  season. 


[  221  3 

When  the  leaves  are  fully  expanded,  the  great 
determination  of  the  sap  is  to  these  new  organs.  And 
hence  a  tree  which  emits  sap  copiously  from  a  wound 
whilst  the  buds  are  opening,  will  no  longer  emit  it  in 
summer  when  the  leaves  are  perfect ;  but  in  the  varia- 
ble weather,  towards  the  ends  of  autumn,  when  the 
leaves  are  falling,  it  will  again  possess  the  power  of 
bleeding  in  a  very  slight  degree  in  the  warmest  days  ; 
but  at  no  other  times. 

In  all  these  circumstances  there  is  nothing  analo- 
gous to  the  irritable  action  of  animal  systems. 

In  animal  systems  the  heart  and  arteries  are  in 
constant  pulsation.  Their  functions  are  unceasingly 
performed  in  all  climates,  and  in  all  seasons ;  in  win- 
ter,  as  well  as  in  spring  ;  upon  the  arctic  snows,  and 
under  the  tropical  suns.  They  neither  cease  in  the 
periodical  nocturnal  sleep,  common  to  most  animals ; 
nor  in  the  long  sleep  of  winter,  peculiar  to  a  few  spe- 
cies. The  power  is  connected  with  animation,  is  lim- 
ited to  beings  possessing  the  means  of  voluntary  lo- 
comotion ;  it  co-exists  with  the  first  appearance  of 
vitality  ;  it  disappears  only  with  the  last  spark  of  life. 

Vegetables  may  be  truly  said  to  be  living  systems, 
in  this  sense,  that  they  possess  the  means  of  convert- 
ing the  elements  of  common  matter  into  organized 
structures,  both  by  assimilation  and  reproduction  ;  but 
we  must  not  suffer  ourselves  to  be  deluded  by  the 
very  extensive  application  of  the  word  life^  to  conceive 
in  the  life  of  plants,  any  power  similar  to  that  produc- 
ing the  life  of  animals.  In  calling  forth  the  vegetable 
functions,  common  physical  agents  alone  seem  to- 


[  222  ] 

operate  ;  but  in  the  animal  system  these  agents  are 
made  subservient  to  a  superior  principle.  To  give  the 
argument  in  plainer  language,  there  are  few  philoso- 
phers who  would  be  inclined  to  assert  the  existence 
of  any  thing  above  common  matter,  any  thing  imma- 
terial in  the  vegetable  ceconomy.  Such  a  doctrine  is 
worthy  only  of  a  poetic  form.  The  imagination  may 
easily  give  Dryads  to  our  trees,  and  Sylphs  to  our 
flowers ;  but  neither  Dryads  nor  Sylphs  can  be  ad- 
mitted in  vegetable  physiology  ;  and  for  reasons  near- 
ly as  strong,  irritability  and  animation  ought  to  be  ex- 
cluded. 

As  the  operation  of  the  different  physical  agents 
upon  the  sap  vessels  of  plants  ceases,  and  fluid  be. 
comes  quiescent,  the  materials  dissolved  in  it  by  heat, 
are  deposited  upon  the  sides  of  the  tubes  now  consi- 
derably  diminished  in  their  diameter;  and  in  conse- 
quence of  this  deposition,  a  nutritive  matter  is  provi- 
ded for  the  first  wants  of  the  plant  in  early  spring,  to 
assist  the  opening  of  the  buds,  and  their  expansion, 
when  the  motion  from  the  want  of  leaves  is  as  yet 
feeble. 

This  beautiful  principle  in  the  vegetable  cecono- 
my  was  first  pointed  out  by  Dr.  Darwin  ;  and  Mr. 
Knight  has  given  a  number  of  experimental  elucida- 
tions of  it. 

Mr.  Knight  made  numerous  incisions  into  the  al- 
burnum of  the  sycamore  and  the  birch,  at  different 
heights ;  and  in  examining  the  sap  that  flowed  from 
them,  he  found  it  piore  sweet  and  mucilaginous  in 
proportion  as  the  aperture  from  which  it  flowed  was 


[  22S  3 

elevated ;  which  he  could  ascribe  to  no  other  cause 
than  to  its  having  dissolved  sugar  and  mucilage, 
which  had  been  stored  up  through  the  winter. 

He  examined  the  alburnum  in  different  poles  of 
oak  in  the  same  forest :  of  which  some  had  been  fel- 
led in  winter,  and  others  in  summer  ;  and  he  always 
found  most  soluble  matter  in  the  wood  felled  in  win- 
ter, and  its  specific  gravity  was  likewise  greater. 

In  all  perennial  trees  this  circumstance  takes 
place  ;  and  likewise  in  grasses  and  shrubs.  The  joints 
of  the  perennial  grasses  contain  more  saccharine  and 
mucilaginous  matter  in  winter  than  at  any  other  sea- 
son ;  and  this  is  the  reason  why  the  fiorin  or  Agros- 
tis  alba,  which  abounds  in  these  joints,  affords  so  use- 
ful a  winter  food. 

The  roots  of  shrubs  contain  the  largest  quantity 
of  nourishing  matter  in  the  depth  of  winter  ;  and  the 
bulb  in  all  plants  pjossessing  it,  is  the  receptacle  in 
which  nourishment  is  hoarded  up  during  winter. 

In  annual  plants  the  sap  seems  to  be  fully  ex- 
hausted of  all  its  nutritive  matter  by  the  production  of 
flowers  and  seeds  3  and  no  system  exists  by  ^which  it 
can  be  preserved. 

When  perennial  grasses  are  cropped  very  close 
by  feeding  cattle  late  in  autumn,  it  has  been  often  ob- 
served by  farmers,  that  they  never  rise  vigorously 
in  the  spring  5  and  this  is  owing  to  the  removal  of 
that  part  ot  the  stalk  which  would  have  afforded  them 
concrete  sap,  their  first  nourishment. 

Ship  builders  prefer  for  their  purposes  that  kind 
of  oak  timber  afforded  by  trees  that  have  had  their 


C  224  3 

bark  stripped  ofF  in  spring,  and  which  have  been  cut 
in  the  autumn  or  winter  following.  The  reason  of 
the  superiority  of  this  timber  is,  that  the  concrete 
sap  is  expended  in  the  spring  in  the  sprouting  of  the 
leaf;  and  the  circulation  being  destroyed,  it  is  not 
formed  anew  ;  and  the  wood  having  its  pores  free 
from  saccharine  matter,  is  less  liable  to  undergo  fer- 
mentation from  the  action  of  moisture  and  air. 

In  perennial  trees  a  new  alburnum,  and  conse- 
quently a  new  system  of  vessels,  is  annually  produc- 
ed, and  the  nutriment  for  the  next  year  deposited  in 
them  ;  so  that  the  new  buds,  like  the  plume  of  the 
seed,  are  supplied  with  a  reservoir  of  matter  essential 
to  their  first  development. 

The  old  alburnum  is  gradually  converted  into 
heart-wood,  and  being  constantly  pressed  upon  by 
the  expansive  force  of  the  new  fibres,  becomes  harder, 
denser,  and  at  length  loses  altogether  its  vascular 
structure ;  and  in  a  certain  time  obeys  the  common 
laws  of  dead  matter,  decays,  decomposes,  and  is  con- 
verted into  aeriform  and  carbonic  elements ;  into  those 
principles  from  which  it  was  originally  formed. 

The  decay  of  the  heart- wood  seems  to  constitute 
the  great  limit  to  the  age  and  size  of  trees.  And  in 
young  branches  from  old  trees,  it  is  much  more  liable 
to  decompose  than  in  similar  branches  from  seedlings. 
This  is  likewise  the  case  with  grafts.  The  graft  is 
only  nourished  by  the  sap  of  the  tree  to  which  it  is 
transferred  ;  its  properties  are  not  changed  by  it ;  the 
leaves,  blossoms,  and  fruits  are  of  the  same  kind  as  if 
it  had  vegetated  upon  its  parent  stock.     The  only  ad- 


C  225  J 

vantage  to  be  gained  in  this  way,  is  the  affording  to  a 
graft  from  an  old  tree  a  more  plentiful  and  healthy 
food  than  it  could  have  procured  in  its  natural  state  ; 
it  is  rendered  for  a  time  more  vigorous,  and  produces 
fairer  blossoms  and  richer  fruits.  But  it  partakes  not 
merely  of  the  obvious  properties,  but  likewise  of  the 
infirmities  and  dispositions  to  old  age  and  decay,  of 
the  tree  whence  it  sprung. 

This  seems  to  be  distinctly  shewn  by  the  obser- 
vations and  experiments  of  Mr.  Knight.  He  has,  in  a 
nuniber  of  instances,  transferred  the  young  scions  and 
healthy  shoots  from  old  esteemed  fruit-bearing  trees 
to  young  seedlings.  They  flourished  for  two  or  three 
years;  but  they  soon  became  diseased  and  sickly  like 
their  parent  trees. 

It  is  from  this  cause  that  so  many  of  the  apples 
formerly  celebrated  for  their  taste  and  their  uses  in  the 
manufacture  of  cyder  are  gradually  deteriorating,  and 
many  will  soon  disappear.  The  golden  pippin,  the 
red  streak,  and  the  moil,  so  excellent  in  the  beginning 
of  the  last  century,  are  now  in  the  extremest  stage  of 
their  decay;  and  however  carefully  they  are  ingrafted, 
they  merely  tend  to  multiply  a  sickly  and  exhausted 
variety. 

The  trees  possessing  the  firmest  and  the  least 
porous  heart-wood  are  the  longest  in  duration. 

In  general  the  quantity  of  charcoal  afforded  by 
woods,  offers  a  tolerable  accurate  indication  of  their 
durability:  those  most  abundant  in  charcoal  and  earthy 
matter  are  most  permanent;  and  those  that  contain  the 


g2 


226 


largest  proportion  of  gaseous  elements  are  the  mosf. 
destructible. 

Amongst  our  own  trees,  the  cheshut  and  the  oak, 
are  pre-eminent  as  to  durability;  and  the  chesnut  af- 
fords rather  more  carbonaceous  matter  than  the 
oak. 

In  old  Gothic  buildings  the^e  woods  have  been 
sometimes  mistaken  one  for  the  other;  but  they  may 
be  easily  known  by  this  circumstance,  that  the  pores 
in  the  alburnum  of  the  oak  are  much  larger  and  more 
thickly  set,  and  are  easily  distinguished;  whilst  the 
pores  in  the  chesnut  require  glasses  to  be  seen  dis- 
tinctly. 

In  consequence  of  the  slow  decay  of  the  heart- 
wood  of  the  oak  and  the  chesnut,  these  trees  under 
favourable  circumstances  attain  an  age  w^hich  cannot 
be  much  short  of  a  1000  years. 

The  beech,  the  ash,  and  the  sycamore,  most  like- 
ly never  live  half  as  long.  The  duration  of  the  apple 
tree  is  not  probably,  much  more  than  200  years;  but 
the  pear  tree,  according  to  Mr.  Knight,  lives  through 
double  this  period;  most  of  our  best  apples  are  sup- 
posed to  have  been  introduced  into  Britain  by  a  fruit- 
erer of  Henry  the  Eighth,  and  they  are  now  in  a  state 
of  old  age. 

The  oak  and  chesnut  decay  much  sooner  in  ^ 
moist  situation,  than  in  a  dry  and  sandy  soil;  and  their 
timber  is  less  firm.  The  sap  vessels  in  such  cases  are 
more  expanded,  though  less  nourishing  matter  is  car- 
ried into  them;  and  the  general  texture  of  the  forma- 
tions of  wood  necessarily  less  firnl.    Such  wood  splits 


[  227  ] 

more  easily,  ai>d  is  more  liable  to  be  afFected  by  varia- 
tions in  the  state  of  the  atmosphere. 

The  same  trees,  in  general,  are  much  longer  lived 
In  the  northern  than  in  the  southern  cHmates.  The 
reason  seems  to  be,  that  all  fermentation  and  decom- 
position are  checked  by  cold;  and  at  very  low  temper- 
atures both  animal  and  vegetable  matters  altogether 
resist  putrefaction:  and  in  the  northern  winter,  not 
only  vegetable  life,  but  likewise  vegetable  decay  must 
be  at  a  stand. 

The  antiputrescent  quality  of  cold  climates  is  ful- 
ly illustrated  in  the  instances  of  the  rhinoceros  and 
mammoth  lately  found  in  Siberia,  entire  beneath  the 
frozen  soil,  in  which  they  must  probably  have  existed 
from  the  time  of  the  deluge.  I  examined  a  part  of  the 
skin  of  the  mammoth,  sent  to  this  country,  on  which 
there  was  some  coarse  hair;  it  had  all  the  chemical 
characters  of  recently  dried  skin. 

Trees  that  grow  in  situations  much  exposed  to 
^''inds,  have  harder  and  firmer  wood  than  such  as  are 
considerably  sheltered.  The  dense  sap  is  determined 
by  the  agitation  of  the  smaller  brances  to  the  trunk 
and  large  branches;  where  the  new  alburnum  formed 
is  consequently  thick  and  firm.  Such  trees  abound  in 
the  crooked  limbs  fitted  for  forming  knee-timber, 
which  is  necessary  for  joining  the  decks  and  sides  of 
ships.  The  gales  in  elevated  situations  gradually  act, 
so  as  to  give  the  tree  the  form  best  calculated  to  resist 
their  effects.  And  the  mountain  oak  rises  robust  and 
sturdy;  fixed  firmly  in  the  soil,  and  able  to  oppose  the 
full  force  of  the  tempest. 


C  228  J 

The  decay  of  the  best  varieties  of  fruit-bearing 
trees  which  have  been  distributed  through  the  country 
by  grafts,  is  a  circumstance  of  great  importance. 
There  is  no  mode  of  preserving  them;  and  no  re- 
source, except  that  of  raising  new  varieties  by  seeds. 

Where  a  species  has  been  ameliorated  by  culture, 
the  seeds  it  affords,  other  circumstances  being  similar, 
produce  more  vigorous  and  perfect  plants;  and  in  this 
way  the  great  improvements  in  the  productions  of  our 
fields  and  gardens  seem  to  have  been  occasioned. 

Wheat  in  its  indigenous  state,  as  a  natural  pro- 
duction of  the  soil,  appears  to  have  been  a  very  small 
grass:  and  the  case  is  still  more  remarkable  with  the 
apple  and  the  plum.  The  crab  seems  to  have  been  the 
parent  of  all  our  apples.  And  two  fruits  can  scarcely 
be  conceived  more  different  in  colour,  size,  and  ap- 
pearance than  the  wild  plum  and  the  rich  magnum 

bonum . 

The  seeds  of  plants  exalted  by  cultivation  always 

furnish  large  and  improved  varieties;  but  the  flavour, 
and  even  the  colour  of  the  fruit  seems  to  be  a  matter 
of  accident.  Thus  a  hundred  seeds  of  the  golden 
pippin  will  all  produce  fine  large-leaved  apple  trees, 
bearing  fruit  of  a  considerable  size;  but  the  tastes  and 
colours  of  the  apples  from  each  will  be  different,  and 
none  will  be  the  same  in  kind  as  those  of  the  pippin 
itself.  Some  will  be  sweet,  some  sour,  some  bitter, 
some  mawkish,  some  aromatic;  some  yellow,  some 
green,  some  red,  and  some  streaked:  All  the  apples 
will,  however,  be  much  more  perfect  than  those  from 
the  seeds  of  a  crab,  which  produce  trees  all  of  the  same 
kind,  and  all  bearing  sour  and  diminutive  fruit. 


C         229         3 

The  power  of  the  horticulturist  extends  only  to 
the  muhiplying  excellent  varieties  by  grafting.  They 
cannot  be  rendered  permanent;  and  the  good  fruits  at 
present  in  our  gardens,  are  the  produce  of  a  few  seed- 
lings, selected  probably  from  hundred  of  thousands  ; 
the  results  of  great  labour  and  industry,  and  multipli- 
ed experiments. 

The  larger  and  thicker  the  leaves  of  a  seedling, 
and  the  more  expanded  its  blossoms,  the  more  it  is 
likely  to  produce  a  good  variety  of  fruit.  Short- 
leaved  trees  should  never  be  selected  ;  for  these  ap- 
proach nearer  to  the  original  standard  ;  whereas  the 
other  qualities  indicate  the  influence  of  cultivation. 

In  the  general  selection  of  seeds,  it  would  appear 
that  those  arising  from  the  most  highly  cultivated  va- 
rieties of  plants,  are  such  as  give  the  most  vigorous 
produce ;  but  it  is  necessary  from  time  to  time  to 
change,  and  as  it  were,  to  cross  the  breed. 

By  applying  the  pollen,  or  dust  of  the  stamina 
from  one  variety  to  the  pistil  of  another  of  the  same 
species,  a  new  variety  may  be  easily  produced  ;  and 
Mr.  Knight's  experiments  seem  to  warrant  the  idea^ 
that  great  advantages  may  be  derived  from  this 
method  of  propagation. 

Mr.  Knight's  large  peas  produced  by  crossing 
two  varieties,  are  celebrated  amongst  horticulturists, 
and  will,  I  hope,  soon  be  cultivated  by  farmers. 

I  have  seen  several  of  his  crossed  apples,  which 
promise  to  rival  the  best  of  those  which  are  gradually 
dying  away  in  the  cyder  countries. 


C  230  ] 

And  his  experiments  on  the  crossing  of  wheat, 
which  is  very  easi'y  effected,  merely  by  sowing  the 
different  kinds  together,  lead  to  a  result  which  is  of 
considerable  importance.  He  says,  in  the  Philosophi- 
cal Transactions  for  1799,  "  in  the  years  1795  and 
1796,  when  almost  the  whole  crop  of  corn  in  the 
island  was  blighted,  the  varieties  obtained  by  crossing 
alone  escaped  though  sown  in  several  soils,  and  in  very 
different  situations." 

The  processes  of  gardening  for  increasing  the 
number  of  fruit-bearing  branches,  and  for  improving 
the  fruit  upon  particular  branches,  will  all  admit  of 
elucidation  from  the  principles  that  have  been  advan- 
ced in  this  Lecture. 

By  making  trees  espaliers,  the  force  of  gravity  is 
particularly  directed  towards  the  lateral  parts  of  the 
branches,  and  more  sap  determined  towards  the  fruit 
buds  ;  and  hence  they  are  more  likely  to  bear  when 
in  a  horizontal  than  when  in  a  vertical  position. 

The  twisting  of  a  wire,  or  tying  a  thread  round 
a  branch  has  been  often  recommended  as  a  means  of 
making  it  produce  fruit.  In  this  case  the  descent  of 
the  sap  in  the  bark  must  be  impeded  above  the  liga- 
ture ;  and  more  nutritive  matter  consequently  retain- 
ed and  applied  to  the  expanding  parts. 

In  engrafting,  the  vessels  of  the  bark  of  the  stock 
and  the  graft  cannot  so  perfectly  come  in  contact  as 
the  albur*nous  vessels,  which  are  as  much  more  nu- 
merous, and  equally  distributed  ;  hence  the  circulation 
downwards  is  probably  impeded,  and  the  tendency 
of  the  graft  to  evolve  its  fruit-bearing  buds  increased. 


I         231  3 

By  lopping  trees,  more  nourishment  is  supplit-d 
to  the  remaining  parts  ;  for  the  sap  flows  laterally  as 
well  as  perpendicularly.  The  same  reasons  will  ap- 
ply to  explain  the  increase  of  size  of  fruits  by  dimin- 
ishing the  number  upon  a  tree. 

As  plants  are  capable  of  amelioration  by  peculiar 
methods  of  cultivation,  and  of  having  the  natural  term 
of  their  duration  extended  ;  so,  in  conformity  to  the 
general  law  of  change,  they  are  rendered  unhealthy 
by  being  exposed  to  peculiar  unfavourable  circum- 
stances, and  liable  to  premature  old  age  and  decay. 

The  plants  of  warm  climates  transported  into 
cold  ones,  or  of  cold  ones  transported  into  warm 
ones,  if  not  absolutely  destroyed  by  the  change  of  situ- 
ation, are  uniformly  rendered  unhealthy. 

Few  of  the  tropical  plants,  as  is  well  known,  can 
be  raised  in  this  country,  except  in  hot  houses.  The 
vine  during  the  whole  of  our  summer  may  be  said  to 
be  in  a  feeble  state  with  regard  to  health  ,  and  its 
fruit,  except  in  very  extraordinary  cases,  always  con- 
tains a  superabundance  of  acid.  The  gigantic  pine  of 
the  north,  when  transported  into  the  equatorial  cli- 
mates, becomes  a  degenerated  dwarf;  and  a  great 
number  of  instances  of  the  same  kind  might  be 
brought  forward. 

Much  has  been  written,  and  rnany  very  ingen- 
ious reijiarks  have  been  made  by  different  philoso- 
phers, upon  what  have  been  called  the  habits  of  plants. 
Thus;  in  transplanting  a  tree,  it  dies  or  becomes  un- 
healthy, unless  its  position  with  respect  to  the  sun  is 
the  same  as  before.     The  seeds  brought  from  warm 


I  232  ] 

climates  germinate  here  much  more  early  in  the  sea- 
son than  the  same  species  brought  from  cold  climates. 
The  apple  tree  from  Siberia,  where  the  short  summer 
of  three  months  immediately  succeeds  the  long  winter, 
in  England,  usually  puts  forths  its  blossoms  in  the 
first  year  of  its  transplantation,  on  the  appearance  of 
mild  weather;  and  is  often  destroyed  by  the  late 
frosts  of  the  spring. 

It  is  not  difficult  to  explain  this  principle  so  inti- 
mately connected  with  the  healthy  or  diseased  state  of 
plants.  The  organization  of  the  germ,  whether  in 
seeds  or  buds,  must  be  different  according  as  more  or 
less  heat  or  alternations  of  heat  and  cold  have  affected 
it  during  its  formation  ;  and  the  nature  of  its  expan- 
sion must  depend  wholly  on  this  organization.  In  a 
changeable  chmate  the  formations  will  have  been  inter- 
rupted, and  in  different  successive  layers.  In  an  equa- 
ble temperature  they  will  have  been  uniform  ;  and 
the  operation  of  new  and  sudden  causes  will  of  course 
be  severely  felt. 

The  disposition  of  trees  may,  however,  be  chang- 
ed gradually  in  many  instances  j  and  the  operation  of 
a  new  climate  in  this  way  be  made  supportable.  The 
myrtle,  a  native  of  the  South  of  Europe  inevitably 
dies  if  exposed  in  the  early  state  of  its  growth  to  the 
frosts  of  our  winter ;  but  if  kept  in  a  green-house 
during  the  cold  seasons  for  successive  years,  and 
gradually  exposed  to  low  temperatures,  it  will,  in  an 
advanced  stage  of  growth,  resist  even  a  very  severe 
cold.  And  in  the  south  and  west  of  England  the^ 
myrtle  flourishes,  produces  blossoms  and  seeds,  in 


[  233  1 

consequence  of  this  process,  as  an  unprotected  stan- 
dard tree  ;  and  the  layers  from  such  trees  are  much 
more  hardy  than  the  layers  from  myrtles  reared  with- 
in doors. 

The  arbutus,  probably  originally  from  similar 
cultivation,  has  become  the  principal  ornament  of  the 
lakes  of  the  south  of  Ireland.  It  thrives  even  in  bleak 
mountain  situations;  and  there  can  be  little  doubt  bu.t 
that  the  offspring  of  this  tree  inured  to  a  temperate  cli- 
mate might  be  easily  spread  in  Britain. 

The  same  principles  that  apply  to  the  effects  of 
heat  and  cold  will  likewise  apply  to  the  influence  of 
moisture  and  dryness.  The  layers  of  a  tree  habitua- 
ted to  a  moist  soil  will  die  in  a  dry  one:  even  though 
such  a  soil  is  more  favourable  to  the  general  growth 
of  the  species.  And,  as  was  stated  page  1 69,  trees 
that  have  been  raised  in  the  centre  of  woods  are  soon- 
er or  later  destroyed,  if  exposed  rn  their  adult  state  to 
blasts,  in  consequence  of  the  felling  of  the  surround- 
ing timber. 

Trees,  in  all  cases,  in  which  they  are  exposed  in 
high  and  open  situations  to  the  sun,  the  winds,  and 
the  rain,  as  I  just  now  noticed,  become  low  and  ro- 
bust, exhibiting  curved  limbs,  but  never  straight  and 
graceful  trunks.  Shrubs  and  trees,  on  the  contrary, 
which  are  too  much  sheltered,  too  much  secluded 
from  the  sun  and  wind  extend  exceedingly  in  height; 
but  present  at  the  same  time  slender  and  feeble 
branches,  their  leaves  are  pale  and  sickly,  and  in  ex- 
treme cases  they  do  not  bear  fruit  The  exclusion 
of  light  alone  is  sufficient  to  produce  this  species  of 

H  2 


I         234  ] 

disease,  as  would  appear  from  the  experiments  of 
Bonnet.  This  ingenious  physiologist  sowed  three 
seeds  of  the  pea  in  the  same  kind  of  soil:  one  he  suf- 
fered to  remain  exposed  to  the  free  air;  the  other  he 
inclosed  in  a  tube  of  glass;  and  the  third  in  a  tube  of 
wood.  The  pea  in  the  tube  of  glass  sprouted,  and 
grew  in  a  manner  scarcely  at  all  different  from  that 
under  usual  circumstances;  but  the  plant  in  the  tub^ 
of  wood  deprived  of  light,  became  white,  and  slender, 
and  grew  to  a  much  greater  height. 

The  plants  growing  in  a  soil  incapable  of  supply- 
ing them  with  sufficient  manure  or  dead  organ- 
ized matter,  are  generally  very  low;  having  brown 
or  dark  green  leaves,  and  their  woody  fibre  abounds 
in  earth.  Those  vegetating  in  peaty  soils,  or  in  lands 
too  copiously  suppHed  with  animal  or  vegetable  matter, 
rapidly  expand,  produce  large  bright  green  leaves^ 
abound  in  sap,  and  generally  blossom  prematurely. 

Where  a  land  is  too  rich  for  corn  it  is  not  an 
uncommon  practice  to  cut  down  the  first  stalks,  as  by 
these  means  its  exuberance  is  corrected,  and  it  is  less 
likely  to  fall  before  the  grain  is  ripe;  excess  of  poverty 
or  of  richness  is  almost  equally  fatal  to  the  hopes  of 
the  farmer;  and  the  true  constitution  of  the  soil  for  the 
bestxcrop  is  that  in  which  the  earthy  materials,  the 
moisture  and  manure,  are  properly  associated;  and  in 
which  the  decomposable  vegetable  or  animal  matter 
does  not  exceed  one-fourth  of  the  weight  of  the  earthy 
constituents. 

The  canker,  or  erosion  of  the  bark  and  wood,  is 
a  disease  produced  often  in  trees  by  a  poverty  of  soil; 


C  235  ] 

and  it  is  invariably  connected  with  old  age.  The  cause 
seems  to  be  an  excess  of  alkaline  and  earthy  matter 
in  the  descending  sap.  I  have  often  found  carbonate 
of  lime  on  the  edges  of  the  canker  in  apple  trees;  and 
ulmin,  which  contains  fixed  alkali,  is  abundant  in  the 
canker  of  the  elm.  The  old  age  of  a  tree,  in  this  res- 
pect, is  faintly  analogous  to  the  old  age  of  animals,  in 
which  the  secretions  of  solid  bony  matter  are  always  in 
excess,  and  the  tendency  to  ossification  great. 

The  common  modes  of  attempting  to  cure  the 
canker,  are  by  cutting  the  edges  of  the  bark,  binding 
new  bark  upon  it,  or  laying  on  a  plaister  of  earth;  but 
these  methods,  though  they  have  been  much  extolled, 
probably  do  very  little  in  producing  a  regeneration  of 
the  part.  Perhaps  the  application  of  a  weak  acid  to 
the  canker  might  be  of  use;  or  where  the  tree  is  of 
great  value,  it  maybe  watered  occasionally  with  a  very 
diluted  acid.  The  alkaline  and  earthy  nature  of  the 
morbid  secretion  warrants  the  trial;  but  circumstances 
that  cannot  be  foreseen  may  occur  to  interfere  with  the 
success  of  the  experiment. 

Besides  the  diseases  having  their  source  in  the 
constitution  of  the  plant,  or  in  the  unfavourable  opera- 
tion of  external  elements,  there  are  many  others  per- 
haps more  injurious,  depending  upon  the  operations 
and  powers  of  other  living  beings;  and  such  are  the 
most  difficult  to  cure,  and  the  most  destructive  to  the 
labours  of  the  husbandman. 

Parasitical  plants  of  different  species  which  at- 
tach themselves  to  trees  and  shrubs,  feed  on  their 
juices,  destroy  their  health;,  and   finally  their  life. 


C  236  ] 

abound  in  all  climates;  and  are,  perhaps,  the  most  for- 
midable of  the  enemies  of  the  superior  and  cultivated 
vegetable  species. 

The  mildew,  which  has  often  occasioned  great 
havock  in  our  wheat  crops,  and  which  was  particular- 
ly destructive  in  1804,  is  a  species  of  fungus,  so  small 
as  to  require  glasses  to  render  its  form  distinct,  and 
rapidly  propagated  by  it? seeds. 

This  has  been  shewn  by  various  botanists;  and 
the  subject  has  received  a  full  illustration  from  the  en- 
lightened and  elaborate  researches  of  the  President  of 
the  Royal  Society. 

The  fungus  rapidly  spreads  from  stalk  to  stalk, 
fixes  itself  in  the  cells  connected  with  the  common 
tubes,  and  carries  away  and  consumes  that  nourish- 
ment which  should  have  been  appropiated  to  the 
grain. 

No  remedy  has  as  yet  been  discovered  for  this 
disease;  but  as  the  fungus  increases  by  the  diffusion  of 
its  seeds,  great  care  should  be  taken  that  no  mildewed 
straw  is  carried  in  the  manure  used  for  corn;  and  in 
the  early  crop,  if  mildew  is  observed  upon  any  of  the 
«talks  of  corn,  they  should  be  carefully  removed  and 
treated  as  weeds. 

The  popular  notion  amongst  farmers,  that  a  bar- 
berry-tree  in  the  neighbourhood  of  a  field  of  wheat  of- 
ten produces  the  mildew,  deserves  examination.  This 
tree  is  frequently  covered  with  a  fungus,  which  if  it 
should  be  shewn  to  be  capable  of  degenerating  into  the 
wheat  fungus  would  offer  an  easy  explanation  of  the 
effect. 


[         237         3 

There  is  every  reason  to  believe,  from  the  re-» 
searches  of  Sir  Joseph  Banks,  that  the  smut  in  wheat 
is  produced  by  a  very  small  fungus  which  fixes  on 
the  grain  :  the  products  that  it  affords  by  analysis  are 
similar  to  those  afforded  by  the  puff-ball ;  and  it  is 
difficult  to  conceive,  that  without  the  agency  of  some 
organized  structure,  so  complete  a  change  should  be 
effected  in  the  constitution  of  the  grain. 

The  mistletoe  and  the  ivy,  the  moss  and  the 
lichen,  in  fixing  upon  trees,  uniformly  injure  their  ve- 
getative processess,  though  in  very  different  degrees. 
They  are  supported  from  the  lateral  sap  vessels,  and 
deprive  the  branches  above  of  a  part  of  their  nourish- 
ment. 

The  insect  tribes  are  scarcely  less  injurious  than 
the  parasitical  plants. 

To  enumerate  all  the  animal  destroyers  and  ty- 
rants of  the  vegetable  kingdom  would  be  to  give  a  ca- 
talogue of  the  greater  number  of  the  classes  in  zoolo- 
gy. Every  species  of  plant  almost  is  the  peculiar 
resting  place,  or  dominion  of  some  insect  tribe  ;  and 
from  the  locust,  the  caterpillar,  and  snail,  to  the  mi- 
nute aphis,  a  wonderful  variety  of  the  inferior  insects 
are  nourished,  and  live  by  their  ravages  upon  the  ve- 
getable world. 

I  have  already  referred  to  the  insect  which  feeds 
on  the  seed-leaf  of  the  turnip. 

The  Hessian  fly,  still  more  destructive  to  wheat, 
has  in  some  seasons  threatened  the  United  States  with 
a  famine.     And  the  French  government  is*  at  this 


*  January  1813. 


[  238  ] 

time  issuing  decrees  with  a  view  to  accasion  the  des- 
truction  of  the  larvas  of  the  grasshopper. 

In  general,  wet  weather  is  most  favourable  to  the 
propagation  of  mildew,  funguses,  rust,  and  the  small 
parasitical  vegetables  ;  dry  weather  to  the  increase  of 
the  insect  tribes*     Nature,  amidst  all  her  changes,  is 
continually  directing  her  resources  towards  the  pro- 
duction and  multiplication  of  life ;  and  in  the  wise  and 
grand  economy  of  the  whole  system,  even  the  agents 
that  appear  injurious  to  the  hopes,  and  destructive  to 
the  comforts  of  man,  are  in  fact  ultimately  connected 
with  a  more  exalted  state  of  his  powers  and  his  condi- 
tion.    His  industry  is  awakened,   his  activity  kept 
alive,  even  by  the  defects  of  climates  and  season.    By 
the  acccidents  which  interfere  with  his  efforts,  he  is 
made  to  exert  his  talents,  to  look  farther  into  futurity, 
and  to  consider  the  vegetable  kingdom  not  as  a  secure 
and  inalterable  inheritance,  spontaneously  providing 
for  his  wants  ;  but  as  a  doubtful  and  insecure  posses- 
sion, to  be  preserved  only  by  labour,  and  extended 
and  perfected  by  ingenuity. 


239 


LECTURE  VI. 

Qf  Manures  of  vegetable  and  animal  Origin.  Of  the 
Manner  in  which  they  become  the  Nourish??jent  of  the 
Plant.  Of  Fermentation  and  Putrefaction.  Of  the 
different  Species  of  Manures  of  vegetable  Origin  ;  of 
the  different  Species  of  ayiimal  Origin.  Of  mixed 
Manures.  General  Principles  with  Respect  to  the 
Use  and  Application  of  such  Manures. 

THAT  certain  vegetable  and  animal  substances 
introduced  into  the  soil  accelerate  vegetation  and  in- 
crease the  produce  of  crops,  is  a  fact  known  since  the 
earliest  period  ot  agriculture  ;  but  the  manner  in 
which  manures  act,  the  best  modes  of  applying  them, 
their  relative  value  and  durability,  are  still  subjects  of 
discussion.  In  this  Lectur^I  shall  endeavour  to  lay 
down  some  settled  principles  on  these  objects  ;  they 
are  capable  of  being  materially  elucidated  by  the  re- 
cent discoveries  in  chemistry  ;  and  I  need  not  dwell 
on  their  great  importance  to  farmers. 

The  pores  in  the  fibres  of  the  roots  of  plants  are 
so  small,  that  it  is  with  difficulty  they  can  be  discovered 
by  the  microscope  ;  it  is  not  therefore  probable,  that 
solid  substances  can  pass  into  them  from  the  soil.  I 
tried  an  experiment  gn  this  subject :  some  impalpa- 
ble powdered  charcoal  procured  by  washing  gunpow- 


[         240         J 

del*  was  placed  in  a  phial  containing  pui*  water,  in 
which  a  plant  of  peppermint  was  growing  :  the  roots 
of  the  plant  were  pretty  generally  in  contact  with  the 
charcoal.  The  experiment  was  made  in  the  beginning 
of  May,  1 805  ;  the  gr®wth  of  the  plant  was  very  vi- 
gorous during  a  fortnight,  when  it  was  taken  out  of 
the  phial ;  the  roots  were  cut  through  in  different 
parts ;  but  no  carbonaceous  matter  could  be  disco- 
vered in  them,  nor  were  the  smallest  fibrils  blackened 
by  charcoal,  though  this  must  have  been  the  case  had 
the  charcoal  been  absorbed  in  a  solid  form. 

No  substance  is  more  necessary  to  plants  than 
carbonaceous  matter  ;  and  if  this  cannot  be  introdu- 
ced into  the  organs  of  plants  except  in  a  state  of  solu- 
tion, there  is  every  reason  to  suppose  that  other  sub- 
stances less  essential  will  be  in  the  same  case. 

I  found  by  some  experiments  made  in  1804,  that 
plants  introduced  into  strong  fresh  solutions  of  sugar, 
mucilage,  tanning  principle,  jelly,  and  other  substan- 
ces died  ;  but  that  plants  lived  in  the  same  solutions 
after  they  had  fermented.  At  that  time,  I  supposed 
that  fermentation  was  necessary  to  prepare  the  food 
of  plants  ;  but  1  have  since  found  that  the  deleterious 
effect  of  the  recent  vegetable  solutions  was  owing  to 
their  being  too  concentrated  ;  in  consequence  of  which 
the  vegetable  organs  were  probably  clogged  with  so- 
lid matter,  and  the  transpiration  by  the  leaves  pre- 
vented. In  the  beginning  of  June,  in  the  next  year, 
I  used  solutions  of  the  same  substances,  but  so  much 
diluted,  that  there  was  only  about  aio  part  of  solid  ve- 
getable or  animal  matter  in  the  solutions.     Plants  of 


r     241     3 

mint  grew  luxuriantly  in  all  these  solutions  ;  but  least 
so  in  that  of  the  astringent  matter.  I  watered  some 
spots,  of  grass  in  a  garden  with  the  different  solutions 
separately,  and  a  spot  with  common  water  :  the  grass 
watered  with  solutions  of  jelly,  sugar,  and  mucilage 
grew  most  vigorously  ;  and  that  watered  with  the  so- 
lution of  the  tanning  principle  grew  better  than  that 
watered  with  common  water. 

I  endeavoured  to  ascertain  whether  soluble  vegetable 
substances  passed  in  an  unchanged  state  into  the  roots 
of  plants,  by  comparing  the  products  of  the  analysis 
of  the  roots  of  some  plants  of  mint  which  had  grown, 
some  In  common  water,  some  In  a  solution  of  sugar, 
1 20  grains  of  the  roots  of  the  mint  which  grew  in  the 
solution  of  sugar,  afforded  five  grains  of  pale  green 
extract,  which  had  a  sweetish  taste,  but  which  slightly 
coagulated  by  the  action  of  alcohol.  120  grains  of 
the  roots  of  the  mint  which  had  grown  In  common 
water  yielded  three  grains  and  a  half  of  extract,  which 
was  of  a  deep  olive  colour ;  its  taste  was  sweetish, 
but  more  astringent  than  that  of  the  other  extract, 
and  it  coagulated  more  copiously  with  alcohol. 

These  results,  thoXigh  not  quite  decisive,  favour 
the  opinion  that  soluble  matters  pass  unaltered  Into 
the  roots  of  plants  ;  and  the  Idea  is  confirmed  by  the 
circumstance  that  the  radical  fibres  of  plants  made  to 
grow  In  Infusions  of  madder  are  tinged  red  ;  and  it  may 
be  considered  as  almost  proved  by  the  fact,  that  sub- 
stances which  are  even  poisonous  to  vegetables  are  ab- 
sorbed by  them.  I  Introduced  the  roots  of  a  primrose 
into  a  weak  solution  of  oxide  of  Iron  In  vinegar,  and 

i2 


[  242  ] 

suffered  it  to  remain  in  it  till  the  leaves  became  yel- 
low ;  the  roots  were  then  carefully  washed  in  distil- 
led water,  bruised,  and  boiled  in  a  small  quantity  of 
the  same  fluid  :  the  decoction  of  them  passed  through 
a  filtre  was  examined  by  the  test  of  infusion  of  nut- 
galls  ;  the  decoction  gained  a  strong  tint  of  purple, 
which  proves  that  solution  of  iron  had  been  taken  up 
by  the  vessels  or  pores  in  the  roots. 

Vegetable  and  animal  substances,  as  is  shewn  by 
universal  experience,  are  consumed  in  vegetation  ; 
and  they  can  only  nourish  the  plant  by  aflfording  solid 
matters  capable  of  being  dissolved  by  water,  or  gas- 
eous substances  capable  of  being  absorbed  by  the 
fluids  in  the  leaves  of  vegetables  ;  but  such  parts  of 
them  as  are  rendered  gaseous,  and  that  pass  into  the 
atmosphere,  must  produce  a  comparatively  small  ef- 
fect, for  gasses  soon  become  diffused  through  the 
mass  of  the  surrounding  air.  The  great  object  in  the 
application  of  manure  should  be  to  make  it  afford  as 
much  soluble  matter  as  possible  to  the  roots  of  the 
plants  ;  and  that  in  a  slow  and  gradual  manner,  so 
that  it  may  be  entirely  consumed  in  forming  the  sap 
or  organized  parts  of  the  plant. 

Mucilaginous,  gelatinous,  saccharine,  oily,  and 
extractive  fluids,  and  solution  of  carbonic  acid  in  wa- 
ter, are  substances  that  in  their  unchanged  states  con- 
tain almost  all  the  principles  necessary  for  the  life  of 
plants  ;  but  there  are  few  cases  in  which  they  can  be 
applied  as  manures  in  their  pure  forms  ;  and  vegeta- 
ble manures,  in  general,  contain  a  great  excess  of  fib- 
rous and  insoluble  matter,  which  must  undergo  che- 


C  243  ] 

mical  changes  before  they  can  become  the  food  of 
plants. 

It  will  be  proper  to  take  a  scientific  view  of  the 
nature  of  these  changes  ;  of  the  causes  which  occasion 
them,  and  which  accelerate  or  retard  them  j  and  of 
the  products  they  afford. 

If  any  fresh  vegetable  matter  which  contains  su- 
^ar,  mucilage,  starch,  or  other  of  the  vegetable  com- 
pounds soluble  in  water  be  moistened  and  exposed  to 
air,  at  a  temperature  from  35°  to  80°,  oxygene  will 
soon  be  absorbed,  and  carbonic  acid  formed  ;  heat 
.will  be  produced,  and  elastic  fluids,  principally  car- 
bonic acid,  gaseous  oxide  of  carbon,  and  hydro- car- 
bonate will  be  evolved ;  a  dark  coloured  liquid  of  a 
slightly  sour  or  bitter  taste  will  likewise  be  formed  ; 
and  if  the  process  be  suffered  to  continue  for  a  time 
sufficiently  long,  nothing  solid  will  remain,  except 
earthy  and  saline  matter,  coloured  black  by  charcoal. 

The  dark  coloured  fluid  formed  in  the  fermenta- 
tion always  contains  acetic  acid  ;  and  when  albumen 
or  gluten  exists  in  the  vegetable  substance,  it  likewise 
contains  volatile  alkali. 

In  proportion  as  there  is  more  gluten,  albumen, 
or  matters  soluble  in  water  in  the  vegetable  substances 
exposed  to  fermentation,  so  in  proportion,  all  other 
circumstances  being  equal,  will  the  process  be  more 
rapid.  Pure  woody  fibre  alone  undergoes  a  change 
very  slowly ;  but  its  texture  is  broken  down,  and  it  is 
easily  resolved  into  new  elements  when  mixed  with 
substances  more  liable  to  change,  containing  more 
oxygene  and  hydrogene.  Volatile  and  fixed  oils,  resins 


[  244  ] 

and  wax,  are  more  susceptible  of  change  than  woody 
fibre  when  exposed  to  air  and  water ;  but  much 
less  liable  than  the  other  vegetable  compounds ;  and 
even  the  most  inflammable  substances  by  the  absorp-^ 
tion  of  oxygene,  become  gradually  soluble  in  water. 

Animal  matters  in  general  are  more  liable  to  de- 
compose than  vegetable  substances  ;  oxygene  is  ab- 
sorbed, and  carbonic  acid  and  ammonia  formed  in  the 
process  of  their  putrefaction.  They  produce  foetid 
compound  elastic  fluids,  and  likewise  azote  :  they  af- 
ford dark  coloured  acid  and  oily  fluids,  and  leave  a 
residuum  of  salts  and  earths  mixed  with  carbonace- 
ous matter. 

The  principal  substances  which  constitute  the 
different  parts  of  animals,  or  which  are  found  in  their 
blood,  their  secredons,  or  their  excrements,  are  gela- 
tine, fibrine,  mucus,  fatty,  or  oily  matter,  albumen, 
urea,  uric  acid,  and  different  acid,  saline,  and  earthy 
matter. 

Of  these  gelatiiie  is  the  substance  which  when 
combined  with  water  forms  jelly.     It  is  very  liable  to 
putrefaction.     According  to  M.  M.  Gay  Lussac  and 
Thenar d  3  it  is  composed  of 
47.88   of  carbon, 
27.20*7  —  oxygene, 
7.914  —  hydrogene. 
16.998 

These  proportions  cannot  be  considered  as  defi- 
nite, for  they  do  not  bear  to  each  other  the  ratios 
of  any  simple  muldples  of  the  number  represent- 
ing the  elements  J   the  case  seems  to  be  the  same 


..#  .  IS?' 

[  245  ] 

with  other  animal  compounds :  and  even  in  ve- 
getable substances,  in  general,  as  appears  from  the 
statements  given  in  the  Third  Lecture,  the  propor- 
tions are  far  from  having  the  same  simple' relations 
as  in  the  binary  compounds  capable  of  being  made 
artificially,  such  as  acids,  alkalies,  oxides,  and  in 
salts.   ^ 

Fibrine  constitutes  the  basis  of  the  muscular 
fibre  of  animals,  and  a  similar  substance  may  be  ob- 
tained from  recent  fluid  blood  ^  by  stirring  it  with  a 
stick  the  fibrine  will  adhere  to  the  stick.  It  is  not 
soluble  in  water  j  but  by  the  action  of  acids,  as  Mr. 
Hatchett  has  shewn,  it  becomes  soluble,  and  analo- 
gous to  gelatine.  It  is  less  disposed  to  putrefy  than 
gelatine.  According  to  M.  M.  Gay  Lussac  and  Then- 
ard,  100  parts  of  fibrine  contain 

Of  carbon        -         -         53.360 
- —  oxygene      -         -         19.685 

—  hydrogene  -         -  7.021 

—  azote  -         -  19.934 

Mucus  IS  very  analogous  to  vegetable  gum  in  its 
characters;  and  as  Dr.  Bostock  has  stated,  it  may  be 
obtained  by  evaporating  saliva.  No  experiments  have 
been  made  upon  its  analysis;  but  it  is  probably  similar 
to  gum  in  composition.  It  is  capable  of  undergoing 
putrefaction,  but  less  rapidly  than  fibrine. 

Animal  fat  and  oils  have  not  been  accurately  analy- 
sed J  but  there  is  great  reason  to  suppose  that  their 
composition  is  analogous  to  that  of  similar  substances 
from  the  vegetable  kingdom. 

Albumen  has  been  already  referred  to,  and  its 
analysis  stated  in  the  Third  Lecture. 


L  246  J 

Urea  may  be  obtained  by  the  evaporation  of  hu- 
man urine,  till  it  is  of  the  consistence  of  a  syrup;  and 
the  action  of  alcohol  on  the  crystalline  substance  which 
forms  when  the  evaporated  matter  cools.  In  this 
way  a  solution  of  urea  in  alcohol  is  procured,  and  the 
alcohol  may  be  separated  from  the  urea  i)y  heat. 
Urea  is  very  solCible  in  water,  and  is  precipitated 
from  water  by  diluted  nitric  acid  in  the  form  of 
bright  pearl-coloured  crystals;  this  property  distin- 
guishes it  from  all  other  animal  substances. 

According  to  Fourcroy  and  Vauquelin,  100  parts 
of  urea  when  distilled  yield. 

92.027  parts  of  carbonate  of  ammonia. 
4.608  carburetted  hydrogene  gas. 
3.225  of  charcoal. 
Urea,    particularly  when    mixed    with    albumen  or 
gelatine,  readily  undergoes  putrefaction. 

Uric  add,  as  has  been  shewn  by  Dr.  Egan, 
may  be  obtained  from  human  urine  by  pouring  an 
acid  into  it;  and  it  often  falls  down  from  urine  in 
the  form  of  brick-coloured  crystals.  It  consists  of 
carbon,  hydrogene,  oxygene  and  azote;  but  their 
proportions  have  not  yet  been  determined.  Uric 
acid  is  one  of  the  animal  substances  least  liable  to 
undergo  the  process  of  putrefaction. 

According  to  the  different  proportions  of  these 
principles  in  animal  compounds,  so  are  the  changes 
they  undergo  different.  When  there  is  much  saline 
or  earthy  matter  mixed  or  combined  with  them,  the 
progress  of  their  decomposition  is  less  rapid  than  when 
they  are  principally  composed  of  fibrine,  albumen, 
gelatine,  or  urea. 


.    €    [         247         ] 

The  ammonia  given  off  from  animal  compounds 
in  putrefaction  may  be  conceived  to  be  formed  at  the 
time  of  their  decomposition  by  the  combination  of  hy- 
drogene  and  azote ;  except  this  matter,  the  other  pro- 
ducts of  putrefaction  are  analogous  to  those  afforded 
by  the  fermentation  of  vegetable  substances  ;  and  the 
soluble  substances  formed  abound  in  the  elements, 
which  are  the  constituent  parts  of  vegetables,  in  car- 
bon, hydrogene,  and  oxygene. 

Whenever  manures  consist  principally  of  matter 
soluble  in  water,  it  is  evident  that  their  fermentation 
or  putrefaction  should  be  prevented  as  much  as  pos- 
sible ;  and  the  only  cases  in  which  these  processes  can 
be  useful,  are  when  the  manure  consists  principally 
of  vegetable  or  animal  fibre.  The  circumstances  ne- 
cessary for  the  putrefaction  of  animal  substances  are 
similar  to  those  required  for  the  fermentation  of  vege- 
table substances  ;  a  temperature  above  the  freezing 
point,  the  presence  of  water,  and  the  presence  of  oxy- 
gene, at  least  in  the  first  stage  of  the  process. 

To  prevent  manures  from  decomposing,  they 
should  be  preserved  dry,  defended  from  the  contact 
of  air,  and  kept  as  cool  as  possible. 

Salt  and  alcohol  appear  to  owe  their  powers  of 
preserving  animal  and  vegetable  substances  to  their  at- 
traction for  water,  by  which  they  prevent  Its  decom- 
posing action,  and  likewise  to  their  excluding  air.  The 
use  of  ice  in  preserving  animal  substances  is  owing  to 
its  keeping  their  temperature  low.  The  efficacy  of 
M.  Appert's  method  of  preserving  animal  and  vegeta- 
ble substances,  an  account  of  which  has  been  lately 


% 


i^ 


L         248         ]  - 

publibhed,  entirely  depends  upon  the  exclusion  of  air. 
This  method  is  by  filling  a  vessel  of  tin  plate  or  glass 
with  the  meat  or  vegetables  ;  soldering  or  cementing 
the  top  so  as  to  render  the  vessel  air  tight ;  and  then 
keeping  it  half  immersed  in  a  vessel  of  boiling  water 
for  a  sufficient  time  to  render  the  meat  or  vegetables 
proper  for  food.  In  this  last  process  it  is  probable 
that  the  small  quantity  of  oxygene  remaining  in  the 
vessel  is  absorbed  :  for  on  opening  a  tinned  iron  can- 
ister which  had  been  filled  with  raw  beef  and  exposed 
to  hot  water  the  day  before,  I  found  that  the  minute 
quantity  of  elastic  fluid  which  could  be  procured  from 
it,  was  a  mixture  of  carbonic  acid  gas  and  azote. 

Where  meat  or  vegetable  food  is  to  be  preserved 
on  a  large  scale,  for  the  use  of  the  navy  or  army  for 
instance,  I  am  inclined  to  believe,  that  by  forcibly 
throwing  a  quantity  of  carbonic  acid,  hydrogene,  or 
azote  into  the  vessel,  by  means  of  a  compressing 
pump,  similar  to  that  used  for  making  artificial  Seltzer 
water,  any  change  in  the  substance  would  be  more 
effectually  prevented.  No  elastic  fluid  in  this  case 
would  have  room  to  form  by  the  decomposition  of 
the  meat ;  and  the  tightness  and  strength  of  the  ves- 
sel would  be  proved  by  the  process.  No  putrefaction 
or  fermentation  can  go  on  without  the  generation  of 
elastic  fluid  ;  and  pressure  would  probably  act  with 
as  much  efficacy  as  cold  in  the  preservation  of  animal 
or  vegetable  food. 

As  different  manures  contain  different  propor- 
tions of  the  elements  necessary  to  vegetation,  so  they 
require  a  different  treatment  to  enable  them  to  pro- 


C  249         3 

duce  their  full  effects  in  agriculture.  I  shall  therefore 
describe  in  detail  the  properties  and  nature  of  the 
manures  in  common  use,  and  give  some  general  views 
respecting  the  best  modes  of  preserving  and  applying 
them. 

Ail  green  succulent  plants  contain  saccharine  or 
mucilaginous  matter,  with  v^oody  fibre,  and  readily 
ferment.  They  cannot,  therefore,  if  intended  for  ma- 
nure, be  used  too  soon  after  their  death, 

"When  green  crops  are  to  be  employed  for  enrich- 
ing  a  soil,  they  should  be  ploughed  in,  if  it  be  possi- 
ble, when  in  flower,  or  at  the  time  the  flower  is  begin- 
ing  to  appear,  for  it  is  at  this  period  that  they  contain 
the  largest  quantity  of  easily  soluble  matter,  and  that 
their  leaves  are  most  active  in  forming  nutritive  mat- 
ter. Green  crops,  pond  weeds,  the  paring  of  hedges 
or  ditches,  or  any  kind  of  fresh  vegetable  matter,  re- 
quires no  preparation  to  fit  them  for  manure.  The 
decomposition  slowly  proceeds  beneath  the  soil ;  the 
soluble  matters  are  gradually  dissolved,  and  the  slight 
fermentation  that  goes  on  checked  by  the  want  of  a 
free  communication  of  air,  tends  to  render  the  woody 
fibre  soluble  without  occasioning  the  rapid  dissipation 
of  elastic  matter. 

When  old  pastures  are  broken  up  and  made 
arable,  not  only  has  the  soil  been  enriched  by  the 
death  and  slow  decay  of  the  plants  which  have  left 
soluble  matters  in  the  soil ;  but  the  leaves  and  roots 
of  the  grasses  living  at  the  time  and  occupying  so 
large  a  part  of  the  surface,  afford  saccharine,  mucila- 
ginous, and  extractive  matters,  which  become  imme- 

k2 


[         250         ] 

diatcly  the  food  of  the  crop,  and  the  gradual  decom- 
postion  affords  a  supply  for  successive  years. 

Rape  cake^  which  is  used  with  great  success  as  a 
manure,  contains  a  large  quantity  of  mucilage,  some 
albuminous  matter,  and  a  small  quantity  of  oil.  This 
manure  should  be  used  recent,  and  kept  as  dry  as  pos- 
sible before  it  is  applied.  It  forms  an  excellent  dres- 
sing for  turnip  crops  ;  and  is  most  oeconomically  ap- 
plied by  being  thrown  into  the  soil  at  the  same  time 
with  the  seed.  Whoever  wishes  to  see  this  practice 
in  its  highest  degree  of  perfection,  should  attend  Mr. 
Coke's  annual  sheep-shearing  at  Holkham* 

Malt  dust  consists  chiefly  of  the  infant  radicle 
separated  from  the  grain.  I  have  never  made  any  ex- 
periment upon  this  manure  ;  but  there  is  great  reason 
to  suppose  it  must  contain  saccharine  matter ;  and  this 
will  account  for  its  powerful  effects.  Like  rape  cake 
it  should  be  used  as  dry  as  possible,  and  its  fermenta- 
tion prevented. 

Linseed  cake  is  too  valuable  as  a  food  for  cattle 
to  be  much  employed  as  a  manure  ;  the  analysis  of 
linseed  was  referred  to  in  the  Third  Lecture.  The 
water  in  which  ^^at  and  hemp  are  steeped  for  the  pur- 
pose of  obtaining  the  pure  vegetable  fibre,  has  consi- 
derable fertilizing  powers.  It  appears  to  contain  a 
substance  analogous  to  albumen,  and  likewise  much 
vegetable  extractive  matter.  It  putrefies  very  readily. 
A  certain  degree  of  fermentation  is  absolutely  neces- 
sary to  obtain  the  flax  and  hemp  in  a  proper  state  j 
the  water  to  which  they  have  been  exposed  should 


I  251  3 

therefore  be  used  as  a  manure  as  soon  as  the  vegeta- 
ble fibre  is  removed  from  it. 

Sea  weeds ^  consisting  of  different  species  of  fuci, 
algse,  and  confervas,  are  much  used  as  a  manure  on 
the  sea  coasts  of  Britain  and  Ireland.  By  digesting 
the  common  fucus,  which  is  the  sea  weed  usually  most 
abundant  on  the  coast,  in  boiling  water,  I  obtained 
from  it  one-eighth  of  a  gelatinous  substance  which 
had  characters  similar  to  mucilage.  A  quantity  dis^ 
tilled  gave  nearly  four-fifths  of  its  weight  of  water, 
but  no  ammonia ;  the  water  had  an  empyreumatic  and 
slightly  sour  taste ;  the  ashes  contained  sea  salt,  car- 
bonate of  soda,  and  carbonaceous  matter.  The  gase- 
ous matter  afforded  was  small  in  quantity,  principally 
carbonic  acid  and  gaseous  oxide  of  carbon,  with  a  lit- 
tle hydro-carbonate.  This  manure  is  transient  in  its 
effects,  and  does  not  last  for  more  than  a  single  crop, 
which  is  easily  accounted  for  from  the  large  quantity 
of  water,  or  the  elements  of  water,  it  contains.  It  de- 
cays without  producing  heat  when  exposed  to  the  at- 
mosphere, and  seems  as  it  were  to  melt  down  and  dis- 
solve away.  I  have  seen  a  large  heap  entirely  des- 
troyed in  less  than  two  years,  nothing  remaining  but 
a  little  black  fibrous  matter. 

I  suffered  some  of  the  firmest  part  of  a  fucus  to 
remain  in  a  close  jar  containing  atmospheric  air  for  a 
fortnight :  in  this  time  it  had  become  very  much 
shrivelled  ;  the  sides  of  the  jar  were  lined  with  dew. 
The  air  examined  was  found  to  have  lost  oxygene, 
and  contained  carbonic  acid  gas. 

Sea  weed  is  sometimes  suffered  to  ferment  be- 
fore it  is  used  }  but  this  process  seems  wholly  unne- 


cessary,  for  there  is  no  fibrous  matter  rendered  solu- 
ble in  the  process,  and  a  part  of  the  manure  is  lost. 

The  best  farmers  in  the  west  of  England  use  it 
as  fresh  as  it  can  be  procured  ;  and  the  practical 
results  of  this  mtode  of  applying  it  are  exactly  confor- 
mable to  the  theory  of  its  operation.  The  carbonic 
acid  formed  by  its  incipient  fermentation  must  be  part- 
ly dissolved  by  the  water  set  free  in  the  same  pro- 
cess ;  and  thus  become  capable  of  absorption  by  the 
roots  of  plants. 

The  effects  of  the  sea  weed  as  manure  must  prin- 
cipally depend  upon  this  carbonic  acid,  and  upon  the 
soluble  mucilage  the  weed  contains  ;  and  I  found  that 
some  fucus  which  had  fermented  so  as  to  have  lost 
about  half  its  weight,  afforded  less  than  iV  of  mucila- 
ginous matter  ;  from  which  it  may  be  fairly  conclud- 
ed that  some  of  this  substance  is  destroyed  in  fermen- 
tation. 

Dry  sir  aw  of  wheat,  oats,  barley,  beans  and  peas, 
and  spoiled  hay,  or  any  other  similar  kind  of  dry  ve- 
getable matter  is,  in  all  cases,  useful  manure.  In 
general,  such  substances  are  made  to  ferment  before 
they  are  employed,  though  it  may  be  doubted  whether 
the  practice  should  be  indiscriminately  adopted. 

From  400  grains  of  dry  barley  straw  I  obtained 
eight  grains  of  matter  soluble  in  water,  which  had  a 
brown  colour,  and  tasted  like  mucilage.  From  400 
grains  of  wheaten  straw  I  obtained  five  grains  of  a 
similar  substance. 

There  can  be  no  doubt  that  the  straw  of  differ- 
ent crops  immediately  ploughed  into  the  ground  af- 


C  253  ] 

fords  nourishment  to  plants ;  but  there  is  an  objec- 
tion to  this  method  of  using  straw  from  the  difficulty 
of  burying  long  straw,  and  from  it^  rendering  the 
jiusbandry  foul. 

When  straw  is  made  to  ferment  it  becomes  a 
itiore  manageable  manure ;  but  there  is  likewise  on 
the  whole  a  great  loss  of  nutritive  matter.  More 
manure  is  perhaps  supplied  for  a  single  crop  ;  but  the 
land  is  less  improved  than  it  would  be,  supposing  the 
whole  of  the  vegetable  matter  could  be  finely  divided 
and  mixed  with  the  soil. 

It  is  usual  to  carry  straw  that  can  be  employed 
for  no  other  purpose  to  the  dunghill,  to  ferment,  and 
decompose ;  but  it  is  worth  experiment,  whether  it 
may  not  be  more  oeconomically  applied  when  chopped 
small  by  a  proper  machine,  and  kept  dry  till  it  is 
ploughed  in  for  the  use  of  a  crop.  In  this  case, 
though  it  would  decompose  much  more  slowly  and 
produce  less  effect  at  first,  yet  its  influence  would  be 
much  more  lasting. 

Mere  woody  fibre  seems  to  be  the  only  vegetable 
matter  that  requires  fermentation  to  render  it  nutritive 
to  plants.  Tanners  spent  hark  is  a  substance  of  this 
kind.  Mr.  Young,  in  his  excellent  Essay  on  Ma- 
nures, which  gained  him  the  Bedfordian  medal  of  the 
Bath  Agricultural  Society,  states,  "  that  spent  bark 
seemed  rather  to  injure  than  assist  vegetation ;" 
which  he  attributes  to  the  astringent  matter  that  it  con- 
tains. But  in  fact  it  is  freed  from  all  soluble  sub- 
stances, by  the  operation  of  water  in  the  tan^pit ;  and 
If  injurious  to  vegetation,  the  effect  is  probably  owing 


I         254         ] 

to  Its  agency  upon  water,  or  to  its  mechanical  effects. 
It  is  a  substance  very  absorbent  and  retentive  of  mois- 
ture, and  yet  not  penetrable  by  the  roots  of  plants. 

Inert  peaty  matter  is  a  substance  of  the  same  kind. 
It  remains  for  years  exposed  to  water  and  air  without 
undergoing  change  ;  and  in  this  state  yields  little  or 
no  nourishment  to  plants. 

Woody  fibre  will  not  ferment  unless  some  sub- 
stances  are  mixed  with  it  which  act  the  same  part  as 
the  mucilage,  sugar,  and  extractive  or  albuminous 
matters,  with  which  it  is  usually  associated  in  herbs 
and  succulent  vegetables.  Lord  Meadowbank  has 
judiciously  recommended  a  mixture  of  common  farm- 
yard dung  for  the  purpose  of  bringing  peats  into  fer- 
mentation ;  any  putrescible  or  fermentable  substance 
will  answer  the  end  ;  and  the  more  a  substance  heats, 
and  the  more  readily  it  ferments,  the  better  will  it  be 
fitted  for  the  purpose. 

Lord  Meadowbank  states,  that  one  part  of  dung 
is  sufficient  to  bring  three  or  four  parts  of  peat  into  a 
state  in  which  it  is  fitted  to  be  applied  to  land  ;  but  of 
course  the  quantity  must  vary  according  to  the  nature 
of  the  dung  and  of  the  peat.  In  cases  in  which  some 
living  vegetables  are  mixed  with  the  peat,  the  fermen- 
tation will  be  more  readily  effected. 

Tanners  spent  bark,  shavings  of  wood  and  saw 
dust,  will  probably  require  as  much  dung  to  bring 
them  into  fermentation  as  the  worst  kind  of  peat. 

Woody  fibre  may  be  likewise  prepared  so  as  to 
become  a  manure  by  the  action  of  lime.  This  subject 
I  shall  discuss  in  the  next  Lecture,  as  it  follows  na* 


[  255  ] 

rurally  another  series  of  facts,  relating  to  the  effects 
of  lime  in  the  soil. 

It  is  evident  from  the  analysis  of  woody  fibre  by 
M.  M.  Gay  Lussac  and  Thenard,  (which  shews  that  it 
consists  principally  of  the  elements  of  water  and  car- 
bon, the  carbon  being  in  larger  quantities  than  in  the 
other  vegetable  compounds)  that  any  process  which 
tends  to  abstract  carbonaceous  matter  from  it,  must 
bring  it  nearer  in  composition  to  the  soluble  princi- 
ples ;  and  this  is  done  in  fermentation  by  the  absorp- 
tion of  oxygene  and  production  of  carbonic  acid  ;  and 
a  similar  effect,  it  will  be  shewn,  is  produced  by  lime. 

Wood-ashes  imperfectly  formed,  that  is  wood-ashes 
containing  much  charcoal,  are  said  to  have  been  used 
with  success  as  a  manure.  A  part  of  their  effects 
may  be  owing  to  the  slow  and  gradual  consumption 
of  the  charcoal,  which  seems  capable,  under  other 
circumstances  than  those  of  actual  combustion,  of  ab- 
sorbing oxygene  so  as  to  become  carbonic  acid. 

An  April,  1803,  I  inclosed  some  well  burnt 
charcoal  in  a  tube  half  filled  with  pure  water,  and  half 
with  common  air  5  the  tube  was  heripetically  sealed. 
I  opened  the  tube  under  pure  water  in  the  spring  of 
1 804,  at  a  time  when  the  atmospheric  tempei'ature  and 
pressure  were  nearly  the  same  as  at  the  commence- 
ment of  the  experiment.  Some  water  rushed  in ;  and 
on  expelling  a  little  air  by  heat  from  the  tube,  and 
analysing  it,  it  was  found  to  contain  only  seven  per 
cent,  of  oxgene.  The  water  in  the  tube,  when  mixed 
with  limewater,  produced  a  copious  precipitate ;    so 


i:         256         J 

that  carbonic  acid  had  evidently  been  formed  and 
dissolved  by  the  water. 

Manures  from  animal  substances,  in  general,  re- 
quire no  chemical  preparation  to  fit  them  for  the  soil. 
The  great  object  of  the  farmer  is  to  blend  them  with 
earthy  constituents  in  a  proper  state  of  division,  and 
to  prevent  their  too  rapid  decomposition. 

The  entire  parts  of  the  muscles  of  land  animals 
are  not  commonly  used  as  manure,  though  there  are 
many  cases  in  which  such  an  application  might  be 
easily  made.  Horses, dogs, sheep, deer,  and  other  quad- 
rupeds that  have  died  accidentally,  or  of  disease,  after 
their  skins  are  separated,  are  often  suffered  to  remain 
exposed  to  the  air,  or  immersed  in  water  till  they  are 
destroyed  by  birds  or  beasts  of  prey,  or  entirely  de- 
composed 'y  and  in  this  case  most  of  their  organized 
matter  is  lost  for  the  land  in  which  they  lie,  and  a 
considerable  portion  of  it  employed  in  giving  off  nox- 
ious gasses  to  the  atmosphere. 

By  covering  dead  animals  with  five  or  six  times 
their  bulk  of  soil,  mixed  with  one  part  of  lime,  and 
suffering  them  to  remain  for  a  few  months  ;  their  de- 
composition would  impregnate  the  soil  with  soluble 
matters,  so  as  to  render  it  an  excellent  manure  ;  and 
by  mixing  a  little  fresh  quicklime  with  it  at  the  time  of 
its  removal,  the  disagreeable  effluvia  would  be  in  a 
great  measure  destr®yed  ;  and  it  might  be  applied  in 
the  same  way  as  any  other  manure  to  crops. 

Fish  forms  a  powerful  manure  in  whatever  state 
it  is  applied  ;  but  it  cannot  be  ploughed  in  too  fresh, 
though  the  quantity  should  be  limited.     Mr.  Young 


C        257        ]       " 

records  an  experiment,  in  which  herrings  spread  over 
a  field  and  ploughed  in  for  wheat,  produced  so  rank 
a  crop,  that  it  was  entirely  laid  before  harvest. 

The  refuse  pilchards  in  Cornwall  are  used 
throughout  the  county  as  a  manure,  with  excellent 
effects.  They  are  usually  mixed  with  sand  or  soil, 
and  sometimes  with  sea-weed,  to  prevent  them  from 
raising  too  luxuriant  a  crop.  The  effects  are  perceiv- 
ed  for  several  years. 

In  the  fens  of  Lincolnshire,  Cambridgeshire,  and 
Norfolk,  the  little  fish  called  sticklebacks,  are  caught 
in  the  shallow  waters  in  such  quantities,  that  they 
form  a  great  article  of  manure  in  the  land  bordering 
on  the  fens. 

It  is  easy  to  explain  the  operation  of  fish  as  a 
manure.  The  skin  is  principally  gelatine :  which 
from  its  slight  state  of  cohesion  is  readily  soluble  in 
water  ;  fat  or  oil  is  always  found  in  fishes,  either  un- 
der the  skin  or  in  some  of  the  viscera ;  and  their  fib- 
rous matter  contains  all  the  essential  elements  of  vege- 
table substances. 

Amongst  oily  substances,  graves  and  blubber  are 
employed  as  manure.  They  are  both  most  useful  when 
mixed  with  soil,  so  as  to  expose  a  large  surface  to  the 
air,  the  oxygene  of  which  produces  soluble  matter 
from  them.  Lord  Somerville  used  blubber  with  great 
success  at  his  farm  in  Surrey.  It  was  made  into  a 
heap  with  soil,  and  retained  its  powers  of  fertilizing 
for  several  successive  years. 

The  carbon  and  hydrogene  abounding  in  oily 
substances  fully  account  for  their  effects  j  and  their 

L  2 


[         258         ] 

durability  is  easily  explained  from  the  gradual  manner 
in  which  they  change  by  the  action  of  air  and  water. 

Bones  are  much  used  as  a  manure  in  the  neigh- 
bourhood of  London.  After  being  broken  and  boiled 
for  grease,  they  are  sold  to  the  farmer.  The  more 
divided  they  are,  the  more  powerful  are  their  effects. 
The  expense  of  grinding  them  in  a  mill  would  proba- 
bly be  repaid  by  the  increase  of  their  fertilizing  pow- 
ers ;  and  in  the  state  of  powder  they  might  be  used  in 
the  drill  husbandry,  and  delivered  with  the  seed  in  the 
same  manner  as  rape  cake. 

Bone  dust,  and  bone  shavings,  the  refuse  of  the 
turning  manufacture,  may  be  advantageously  employ- 
ed in  the  same  way. 

The  basis  of  bone  is  constituted  by  earthy  salts, 
principally  phosphate  of  lime,  with  some  carbonate  of 
lime  and  phosphate  of  magnesia  j  the  easily  decom- 
posable substances  in  bone  are  fat,  gelatine,  and  cartil- 
age, which  seems  of  the  same  nature  as  coagulated 
albumen. 

According  to  the  analysis  of  Fourcroy  and  Vau- 
quelin,  ox  bones  are  composed 

Of  decomposable  animal  matter       51 

—  phosphate  of  lime      -         -         37.7 

—  carbonate  of  lime      -         -         10 

—  phosphate  of  magnesia        -  1.3 

100 

M.  Merat  Guillot  has  given  the  following  esti- 
mate of  the  composition  of  the  bones  of  different 
animals. 


259 


Bone  of  Calf 

Horse 

Sheep 

Elk 

Hog 

Hare 

Pullet 

Pike 

Carp 


Horses 

Ivory 

Hartshorn 


leeth 


Pho«phat© 
of  linie. 


54 

67.5 
70 
90 

52 
8< 

7a 

64 

45 

85.5 

64 

27 


Carbonate 
of  lime. 


X.25 
< 
1 
1 
1 
1.5 
1 
5 

25 
1 
1 


The  remaining  parts  of  the  100  must  be  consi- 
dered as  decomposable  animal  matter. 

Horn  is  a  still  more  powerful  manure  than  bone, 
as  it  contains  a  larger  quantity  of  decomposable  ani- 
mal matter.  From  500  grains  of  ox  horn  Mr.  Hatch- 
ett  obtained  only  1-5  grains  of  earthy  residuum,  and 
not  quite  half  of  this  was  phosphate  of  lime.  The 
shaving  or  turnings  of  horn  form  an  excellent  ma- 
nure, though  they  are  not  sufficiently  abundant  to  be 
in  common  use.  The  animal  matter  in  them  seems 
ib  be  of  the  nature  of  coagulated  albumen,  and  it  is 
slowly  rendered  soluble  by  the  action  of  water.  The 
earthy  matter  in  horn,  and  still  more  that  in  bones, 
prevents  the  too  rapid  decomposition  of  the  animal 
matter,  and  renders  it  very  durable  in  its  effects. 

Hair^  woollen  rags  znA  feathers  are  all  analogous 
in  composition,  and  principally  consists  of  a  substance 
similar  to  albumen,  united  to  gelatine.  This  is  shewn 
by  the  ingenious  researches  of  Mr.  Hatchett.  The 
theory  of  their  operation  is  similar  to  that  of  bone  and 
horn  shavings. 

The  refuse  of  the  different  manufactures  of  skin 
and  leather  form  very  useful  manures  j  such  as  the 


[       tieo      ] 

shavings  of  the  currier,  furriers'  clippings,  and  the 
offals  of  the  tan-yard  and  of  the  glue-maker.  The 
gelatine  contained  in  every  kind  of  skin  is  in  a  state 
fitted  for  its  gradual  solution  or  decomposition  -,  and 
when  buried  in  the  soil,  it  lasts  for  a  considerable 
time,  and  constantly  affords  a  supply  of  nutritive  mat- 
ter to  the  plants  in  its  neighbourhood. 

Blood  contains  certain  quantities  of  all  the  princi- 
ples found  in  other  animal  substances,  and  is  conse- 
quently a  very  good  manure.  It  has  been  already 
stated  that  it  contains  fibrine  ;  it  likewise  contains  al- 
bumen :  the  red  particles  in  it  which  have  been  sup- 
posed by  many  foreign  chemists  to  be  coloured  by 
iron  in  a  particular  state  of  combination  with  oxygene 
^ind  acid  matter,  Mr.  Brande  considers  as  formed  of 
a  peculiar  animal  substance,  containing  very  little 
iron. 

The  scum  taken  from  the  boilers  of  the  sugar 
bakers,  and  which  is  used  as  manure,  principally  con- 
sists of  bullock's  blood,  which  has  been  employed  for 
the  purpose  of  separating  the  impurities  of  common 
brown  sugar,  by  means  of  the  coagulation  of  its  albu- 
minous matter  by  the  heat  of  the  boiler. 

The  different  species  of  corals,  coralines,  and 
spongesy  must  be  considered  as  substances  of  animal 
origin.  From  the  analysis  of  Mr.  Hatchett,  it  appears 
that  all  these  substances  contain  considerable  quanti- 
ties of  a  matter  analogous  to  coagulated  albumen ;  the 
gponges  afford  likewise  gelatine. 

According  to  Merat  Guillot  white  coral  contains 
equal  parts  of  animal  matter  and  carbonate  of  lime  : 


C         261  3 

red  coral  46.5  of  animal  matter,  and  53.5  of  carbon- 
ate  of  lime ;  articulated  coraline  51  of  animal  matter, 
and  49  of  carbonate  of  lime. 

These  substances  are,  I  believe,  never  used  as  ma- 
nure in  this  country,  except  in  cases  when  they  are  ac- 
cidentally mixed  with  sea  weed  ;  but  it  is  probable  that 
the  coralines  might  be  advantageously  employed,  as 
they  are  found  in  considerable  quantity  on  the  rocks, 
and  bottoms  of  the  rocky  pools  on  many  parts  of  our 
coast,  where  the  land  gradually  declines  towards  the 
sea  ;  and  they  might  be  detached  by  hoes,  and  collect- 
ed without  much  trouble. 

Amongst  excrementations,  animal  substances 
used  as  manures  urine  is  the  one  upon  which  the 
greatest  number  of  chemical  experiments  have  been 
made,  and  the  nature  of  which  is  best  understood. 

The  urine  of  the  cow  contains,  according  to  the 
experiments  of  Mr.  Brande, 

Water         -         -         -         .         -         65 
Phosphate  of  lime         *        .         .  3 

Muriates  of  polassa  and  ammonia     -         15 
Sulphate  of  potassa       -         -         -  6 

Carbonates,  and  potassa,  and  ammonia       4 

Urea 4 

The  urine  of  the  horse,  according  to  Fourcroy 
and  Vauquelin,  contains 

Of  carbonate  of  lime  1 1 

—  carbonate  of  soda       .        -        -         9 

—  benzoate  of  soda        -         -        -       24 

—  Muriate  of  potassa     -        ^         .         0 

—  Urea        -         .        .         -         .         7 
— •  Water  and  mucilage  -        *    940 


[         262         ] 

In  addition  to  these  substances,  Mr.  Brande  found 
in  it  phosphate  of  lime. 

The  urine  of  the  ass,  the  camel,  the  rabbit,  and 
domestic  fowls  have  been  submitted  to  different  ex- 
periments, and  their  constitution  have  been  found  si- 
milar. In  the  urine  of  the  rabbit,  in  addition  to  most 
of  the  ingredients  above  mentioned,  Vauquelin  detect- 
ed gelatine ;  and  the  same  chemist  discovered  uric 
acid  in  the  urine  of  domestic  fowls. 

Human  urine  contains  a  greater  variety  of  con- 
stituents than  any  other  species  examined. 

Urea,  uric  acid,  and  another  acid  similar  to  it  in 
natm*e  called  rosacic  acid,  acetic  acid,  albumen,  gela- 
tine, a  resinous  matter,  and  various  salts  are  found 
in  it. 

The  human  urine  differs  in  composition  accord- 
ing to  the  state  of  the  body,  and  the  nature  of 
the  food  and  drink  made  use  of.  In  many  cases 
of  disease  there  is  a  much  larger  quantity  of  gelatine 
and  albumen  than  usual  in  the  urine ;  and  in  diabetes 
it  contains  sugar. 

It  is  probable  that  the  urine  of  the  same  animal 
must  likewise  differ  according  to  the  different  nature 
of  the  food  and  drink  used  ;  and  this  will  account  for 
discordancies  in  some  of  the  analyses  that  have  been 
published  on  the  subject. 

.  Urine  is  very  liable  to  change  and  to  undergo  the 
putrefactive  process ;  and  that  of  carnivorous  animals 
more  rapidly  than  that  of  graminivorous  animals.  In 
proportion  as  there  is  more  gelatine  and  albumen  in 
urine^  so  in  proportion  does  it  putrify  more  quickly. 


[  263  3 

The  species  of  urine  that  contain  most  albumen, 
gelatine  and  urea,  are  the  best  as  manures  ;  and  all 
urine  contains  the  essential  elements  of  vegetables  in  a 
state  of  solution. 

During  the  putrefaction  of  urine  the  greatest 
part  of  the  soluble  animal  matter  that  it  contains  is 
destroyed  ;  it  should  consequently  be  used  as  fresh 
.as  possible ;  but  if  not  mixed  with  solid  matter,  it 
should  be  diluted  with  water,  as  when  pure  it  contains 
too  large  a  quantity  of  animal  matter  to  form  a  pro- 
per fluid  nourishment  for  absorption  by  the  roots  of 
plants. 

Putrid  urine  abounds  in  ammoniacal  salts ;  and 
though  less  active  than  fresh  urine,  is  a  very  power- 
ful manure. 

According  to  a  recent  analysis  published  by  Ber- 
zelius,  1000  parts  of  urine  are  composed  of 

Water 933 

Urea 30.1 

Uric  acid  -         -         -         .  1 

Muriate  of  ammonia,  free  lactic  acid,"^ 
lactate  of  ammonia  and  animal  >»17.14 
matter  -         -        -        -     J 

The  remainder  different  salts,  phosphates,  sul- 
phates, and  muriates. 

Amongst  excrementitious  solid  substances  used 
as  manures,  one  of  the  most  powerful  is  the  dung  of 
birds  that  feed  on  animal  food^  particularly  the  dung  of 
sea  birds.  The  guano^  which  is  used  to  a  great  extent 
in  South  America,  and  which  is  the  manure  that  fer- 
tilizes the  sterile  plains  of  Peru,  is  a  production  of  this 


C         264         3 

kind.  It  exists  abundantly,  as  we  are  informed  by 
M.  Humboldt,  on  the  small  islands  in  the  south  sea, 
at  Chinche,  Ilo,  Iza,  and  Arica.  50  vessels  are  la- 
den with  it  annually  at  Chinche,  each  of  which  carries 
from  1500  to  2000  cubical  feet.  It  is  used  a  manure 
only  in  very  small  quantities  ;  and  particularly  for 
crops  of  maize.  I  made  some  experiments  on  speci- 
mens of  guano  sent  from  South  America  to  the  Board 
of  Agriculture  in  1805.  It  appeared  as  a  fine  brown 
powder  ;  it  blackened  by  heat,  and  gave  off  strong 
ammoniacal  fumes  ;  treated  with  nitric  acid  it  afford- 
ed uric  acid.  In  1806  M.  M.  Fourcroy  and  Vauque- 
lin  published  an  elaborate  analysis  of  guano.  They 
state  that  it  contains  a  fourth  part  of  its  weight  of  uric 
acid,  partly  saturated  with,ammonia,  and  partly  with 
potassa ;  soms  phosphoric  acid  combined  with  the 
same  bases,  and  likewise  with  lime.  Small  quantities 
of  sulphate  and  muriate  of  potassa.  a  little  fatty  matter, 
and  some  quartzose  sand. 

It  is  easy  to  explain  its  fertilizing  properties  : 
from  its  composition  it  might  be  supposed  to  be  a  very 
powerful  manure.  It  requires  water  for  the  solution 
of  its  soluble  matter  to  enable  it  to  produce  its  full 
beneficial  effect  on  crops. 

The  dung  of  sea  birds  has,  I  believe,  never  been 
used  as  a  manure  in  this  country  ;  but  it  is  probable, 
that  even  the  soil  of  the  small  islands  on  our  coast 
much  frequented  by  them,  would  fertilize.  Some 
dung  of  sea  birds  brought  from  a  rock  on  the  coast  of 
Merionethshire,  produced  a  powerful  but  transient 
effect  on  grass.  It  was  tried,  at  my  request,  by  Sir 
Robert  Vaughan  at  Nannau. 


L  265  J 

The  rains  in  our  climate  must  tend  Very  much 
to  injure  this  species  of  manure,  where  it  is  exposed 
to  them,  soon  after  its  deposition  ;  but  it  may  proba- 
bly be  fomid  in  great  perfection  in  caverns  or  clefts  in 
rocks,  haunted  by  cormorants  and  gulls.  I  examined 
some  recent  cormorant's  dung  which  I  found  on  a 
rock  near  Cape  Lizard  in  Cornwall.  It  had  not  at  all 
the  appearance  of  the  guano  ;  was  of  a  greyish  while 
colour  ;  had  a  very  fcetid  smell  like  that  of  putrid  ani- 
mal matter:  when  acted  on  by  quicklime  it  gave 
abundance  of  ammonia ;  treated  with  nitric  acid  it 
yielded  uric  acid.  f 

Nig/jt  soil,  it  is  well  known,  is  a  very  powerful 
manure,  and  very  liable  to  decompose.  It  differs  in  its 
composition  ;  but  always  abounds  in  substances  com- 
posed of  carbon,  hydrogene,  azote,  and  oxygene. 
From  the  analyses  of  Berzelius,  it  appears  that  a  part 
of  it  is  always  soluble  in  water  ;  and,  in  whatever  state 
it  is  used,  whether  recent  or  fermented,  it  supplies 
abundance  of  food  to  plants. 

The  disagreeable  smell  of  night  soil  may  be  des- 
troyed by  mixing  it  with  quicklime ;  and  if  exposed  to 
the  atmosphere  in  thin  layers  strewed  over  with  quick* 
lime  in  fine  weather,  it  speedily  dries,  is  easily  pulver- 
ised, and  in  this  state  may  be  used  in  the  same  manner 
as  rape  cake,  and  delivered  into  the  furrow  with  the 
seed. 

The  Chinese,  w^ho  have  more  practical  know- 
ledge of  the  use  and  application  of  manures  than  any 
other  people  existing,  mix  their  night  soil  with  one- 
third  of  its  weight  of  a  fat  marie,  make  it  into  cakes, 

m2 


[         ^66         ] 

atid  dry  it  by  exposure  to  the  sun.  These  cakes,  we 
are  informed  by  the  French  missionaries,  have  no  dis-* 
agreeable  smell,  and  form  a  common  article  of  com- 
merce of  the  empire.  v^ 

The  earth,  by  its  absorbent  powers,  probably 
prevents,  to  a  certain  extent,  the  action  of  moisture 
upon  the  dung,  and  likewise  defends  it  from  the  ef- 
fects of  air. 

After  night  soil,  pigeons*  dung  come  next  in  or- 
der, as  to  fertilizing  power.  I  digested  100  grains  of 
pigeons'  dung  in  hot  water  for  some  hours,  and  ob- 
tained from  it  23  grains  of  soluble  matter  ;  which  af- 
forded abundance  of  carbonate  of  ammonia  by  distil- 
lation ;  and  left  carbonaceous  matter,  saline  matter 
principally  common  salt,  and  carbonate  of  lime  as  a 
residuum.  Pigeons'  dung  when  moist  readily  fer- 
ments, and  after  fermentation  contains  less  soluble 
matter  than  before:  from  100  parts  of  fermented 
pigeons'  dung,  I  obtained  only  eight  parts  of  soluble 
matter,  which  gave  proportionally  less  carbonate  of 
ammonia  in  divStillation  than  recent  pigeons'  dung. 

It  is  evident  that  this  manure  should  be  applied 
as  new  as  possible  ;  and  when  dry,  it  may  be  employ- 
ed in  the  same  manner  as  the  other  manures  capable 
of  being  pulverised. 

The  soil  in  woods  where  great  flocks  of  wood- 
pigeons  roost,  is  often  highly  impregnated  with  their 
dung,  and  it  cannot  be  doubted,  would  form  a  valuable 
manure.  I  have  found  such  soil  yield  ammonia  when 
distilled  with  lime.  In  the  winter  likewise  it  usually 
contains  abundance  of  vegetable  matter,  the  remains 


C         267         ] 

of  decayed  leaves  ;  and  the  dung  tends  to  bring  the 
vegetable  matter  into  a  state  of  solution. 

The  dung  oi  domestic  fowls  approaches  very  near- 
ly in  its  nature  to  pigeons'  dung.  Uric  acid  has  been 
found  in  it.  It  gives  carbonate  of  ammoniji  by  distilla- 
tion, and  immediately  yields  soluble  matter  to  water. 
It  is  very  liable  to  ferment. 

The  dung  of  fowls  is  employed  in  common  with 
that  of  pigeons  by  tanners  to  bring  on  a  slight  degree 
of  putrefaction  in  skins  that  are  to  be  used  for  making 
soft  leather ;  for  this  purpose  the  dung  is  diffused 
through  water.  In  this  state  it  rapidly  undergoes  pu- 
trefaction, and  brings  on  a  similar  change  in  the  skin. 
The  excrements  of  dogs  are  employed  by  the  tanner 
with  similar  effects.  In  all  cases,  the  contents  of  the 
grainer^  as  the  pit  is  called  in  which  soft  skins  are  pre- 
pared by  dung,  must  form  a  very  useful  manure. 

Rabbits*  dung  has  never  been  analysed.  It  is 
used  with  great  success  as  a  manure  by  Mr.  Fane^ 
who  finds  it  profitable  to  keep  rabbits  in  such  a  man- 
ner as  to  preserve  their  dung.  It  is  laid  on  as  fresh 
as  possible,  and  is  foun^d  better  the  less  it  has  fer- 
mented. 

The  dung  of  cattle y  oxen  and  cows^  has  been  che- 
mically examined  by  M.  M.  Einhof  and  Thaer.  They 
found  that  it  contained  matter  soluble  in  water  ;  and 
that  it  gave  in  fermentation  nearly  the  same  products 
as  vegetable  substances,  absorbing  oxygene  and  pro- 
ducing carbonic  acid  gas. 

The  recent  dung  of  sheep^  and  of  deer^  afford, 
when  long  boiled  in  water,  soluble  matters,  which 


equal  from  two  to  three  per  cent,  of  their  weight.  I 
have  examined  these  soluble  substances  procured  by 
solution  and  evaporation  ;  they  contain  a  very  small 
quantity  of  matter  analogous  to  animal  mucus  ;  and 
are  principally  composed  of  a  bitter  extract,  soluble 
both  in  water  and  in  alcohol.  They  give  ammoniacal 
fumes  by  distillation  ;  and  appear  to  differ  very  little 
in  composition. 

I  watered  some  blades  of  grass  for  several  suc- 
cessive days  with  a  solution  of  these  extracts  ;  they 
evidently  became  greener  in  consequence,  and  grew 
more  vigorously  than  grass  in  other  respects,  under 
the  same  circumstances. 

The  part  of  the  dung  of  cattle,  sheep,  and  deer, 
not  soluble  in  water,  appears  to  be  mere  woody  fibre, 
and  precisely  analogous  to  the  residuum  of  those  ve- 
getables that  form  their  food  after  they  have  been  de- 
prived of  all  their  soluble  materials. 

The  dung  of  horses  gives  a  brown  fluid,  which 
when  evaporated,  yields  a  bitter  extract,  which  affords 
ammoniacal  funics  more  copiously  than  that  from  the 
dung  of  oxen. 

If  the  pure  dung  of  cattle  is  to  be  used  as  manure 
like  the  other  species  of  dung  which  have  been  men- 
tioned, there  seems  no  reason  why  it  should  be  made  to 
ferment  except  in  the  soil ;  or  if  suffered  to  ferment, 
it  should  be  only  in  a  very  slight  degree.  The  grass 
in  the  neighbourhood  of  recently  voided  dung,  is  al- 
ways  coarse  and  dai'k  green ;  some  persons  have  at- 
tributed this  to  a  noxious  quality  in  unfcrmented 
dung ;  but  it  seems  to  be  rather  the  result  of  an  excess 
of  food  furnished  to  the  plants. 


C         269         ] 

The  question  of  the  proper  mode  of  the  applica- 
tion of  the  dung  of  horses  and  cattle,  however,  pro- 
perly belongs  to  the  subject  of  composite  manures^  for 
it  is  usually  mixed  in  the  farm-yard  with  straw,  ofFal, 
chaff,  and  various  kind  of  litter;  and  itself  contains  a 
large  proportion  of  fibrous  vegetable  matter. 

A  slight  incipient  fermentation  is  undoubtedly  of 
use  in  the  dunghill;  for  by  means  of  it  a  disposition  is 
brought  on  in  the  woody  fibre  to  decay  and  dissolve, 
when  it  is  carried  to  the  land,  or  ploughed  into  the 
soil;  and  woody  fibre  is  always  in  great  excess  in  the 
refuse  of  the  farm. 

Too  great  a  degree  of  fermentation  is,  however, 
very  prejudicial  to  the  composite  manure  in  the  dung- 
hill; it  is  better  that  there  should  be  no  fermentation 
at  all  before  the  manure  is  used,  than  that  it  should  be 
carried  too  far.  This  must  he  obvious  from  what 
has  been  already  stated  in  this  Lecture.  The  excess 
of  fermentation  tends  to  the  destruction  and  dissipa- 
tion of  the  most  useful  part  of  the  manure;  and  the 
ultimate  results  of  this  process  are  like  those  of  com- 
bustion. 

It  is  a  common  practice  amongst  farmers,  to  suf- 
fer the  farm-yard  dung  to  ferment  till  the  fibrous 
texture  of  the  vegetable  matter  is  entirely  broken 
down;  and  till  the  manure  becomes  perfectly  cold, 
and  so  soft  as  to  be  easily  cut  by  the  spade. 

Independent  of  the  general  theoretical  views  un- 
favourable to  this  practice  founded  upon  the  nature 
and  composition  of  vegetable  substances,  there  are 
many  arguments  and  facts  which  shew  that  it  is  pre- 
judicial to  the  interests  of  the  farmer. 


C  270  ] 

During  the  violent  fermentation  which  is  neces- 
sary for  reducing  farm-yard  manure  to  the  state  in 
which  it  is  called  sJoort  mucky  not  only  a  large  quantity 
of  fluid,  but  likewise  a  gaseous  matter  is  lostj  so  much 
so  that  the  dung  is  reduced  one  half,  or  two-thirds  in 
weight;  and  the  principal  elastic  matter  disengaged,  is 
carbonic  acid  with  some  ammonia;  and  both  these,  if 
retained  by  the  moisture  in  the  soil,  as  has  been  stated 
before,  are  capable  of  becoming  an  useful  nourish- 
ment of  plants. 

In  October,  1808,  I  filled  a  large  retort  capable 
of  containing  three  pints  of  water,  with  some  hot  fer- 
menting manure,  consisting  principally  of  the  litter 
and  dung  of  cattle;  I  adapted  a  small  receiver  to  the 
retort,  and  connected  the  whole  with  a  mercurial  pneu- 
matic apparatus,  so  as  to  collect  the  condensible  and 
elastic  fluids  which  might  rise  from  the  dung.  The 
receiver  soon  became  lined  with  dew,  and  drops  be- 
gan in  a  few  hours  to  trickle  down  the  sides  of  it. 
Elastic  fluid  likewise  was  generated;  in  three  days  35 
cubical  inches  had  been  formed,  w^hich  when  analy- 
sed, were  found  to  contain  21  cubical  inches  of  car- 
bonic acid,  the  remainder  was  hydroc^rbonate  mixed 
with  some  azote,  probably  no  more  than  existed  in 
the  common  air  in  the  receiver.  The  fluid  matter 
collected  in  the  receiver  at  the  same  time  amounted 
to  nearly  half  an  ounce.  It  had  a  sahne  taste,  and  a 
disagreeable  smell,  and  contained  some  acetate  and 
carbonate  of  ammonia. 

Finding  such  products  given   off  from   ferment- 
ing litter,   I  introduced  the  beak  of  another  retort 


[       ^271  J 

filled  with  similar  dung  very  hot  at  the  time,  into 
the  soil  amongst  the  roots  of  some  grass  in  the  bor- 
der of  a  garden;  in  less  than  a  week  a  very  distinct  ef- 
fect was  produced  upon  the  grass;  upon  the  spot 
exposed  to  the  influence  of  the  matter  disenga- 
ged in  fermentation,  it  grew  with  much  more  lux- 
uriance than  the  grass  in  any  other  part  of  the  gar- 
den. 

Besides  th^  dissipation  of  gaseous  matter  when 
fermentation  is  pushed  to  the  extreme,  there  is  ano- 
ther disadvantage  in  the  loss  of  heat^  which,  if  excited 
in  the  soil,  is  useful  in  promoting  the  germination  of 
the  seed,  and  in  assisting  the  plant  in  the  first  stage  of 
its  growth,  when  it  is  most  feeble  and  most  liable  to 
disease:  and  the  fermentation  of  manure  in  the  soil 
must  be  particularly  favourable  to  the  wheat  crop  in 
preserving  a  genial  temperature  beneath  the  surface 
late  in  autumn,  and  during  winter. 

Again,  it  is  a  general  principal  in  chemistry,  that 
in  all  cases  of  decomposition,  substances  combine 
much  more  readily  at  the  moment  of  their  disengage- 
ment, than  after  they  have  been  perfectly  formed. — 
And  in  fermentation  beneath  the  soil  the  fluid  matter 
produced  is  applied  instantly,  even  whilst  it  is  warm, 
to  the  organs  of  the  plant,  and  consequently  is  more 
likely  to  be  efficient,  than  in  manure  that  has  gone 
through  the  process;  and  of  which  all  the  principles 
have  entered  into  new  combinations. 

In  the  writings  of  scientific  agriculturists,  a  great 
mass  of  facts  may  be  found  in  favour  of  the  applica- 
tion of  farm-yard  dung  in  a  recent  state.  Mr.  Young, 
m  the  Essay  on  Manures,  which  I  have  already  quoted, 


C         272         ] 

adduces  a  number  of  excellent  authorities  ia  support 
of  the  plan.  Many  who  doubted,  have  been  lately  con- 
vinced; and  perhaps  there  is  no  subject  of  investiga- 
tion in  which  there  is  such  a  union  of  theoretical  and 
practical  evidence.  I  have  myself  within  the  last  ten 
years  witnessed  a  number  of  distinct  proofs  on  the 
subject.  I  shall  content  myself  with  quoting  that 
which  ought  to  have,  and  which  I  am  sure  will  have, 
the  greatest  weigftt  amongst  agriculturists.  Within 
the  last  seven  years  Mr.  Coke  has  entirely  given  up 
the  system  formerly  adopted  on  his  farm  of  applying 
fermented  dung;  and  he  informs  me,  that  his  crops 
have  been  since  as  good  as  they  ever  were,  and  that 
his  manure  goes  nearly  twice  as  far. 

A  great  objection  against  slightly  fermented  dung 
is,  that  weeds  spring  up  more  luxuriantly  where  it  is 
applied.  If  there  are  seeds  carried  out  in  the  dung 
they  certainly  will  germinate;  but  it  is  seldom  that  this 
(ian  be  the  case  to  any  extent;  and  if  the  land  is  not 
cleansed  of  weeds,  any  kind  of  manure  fermented  or 
unfermented  will  occasion  their  rapid  growth.  If 
slightly  fermented  farm-yard  dung  is  used  as  a  top 
dressing  for  pastures,  the  long  straws  and  unfermented 
vegetable  matter  remaining  on  the  surface  should  be 
removed  as  soon  as  the  grass  begins  to  rise  vigorous- 
ly by  raking,  and  carried  back  to  the  dunghill:  in  this 
case  no  manure  will  be  lost,  and  the  husbandry  will 
be  at  once  clean  and  oeconomical. 

In  cases  when  farm-yard  dung  cannot  be  immedi- 
ately applied  to  crops,  the  destructive  fermentation  of 
it  should  be  prevented  as  much  as  posssible:  the  prin- 


C  273  J 

ciples  on  which  this  may  be  effected  have  been  allud- 
ed  to. 

The  surface  should  be  defended  as  much  as  pos- 
sible from  the  oxygene  of  the  atmosphere  ;  a  compact 
marie,  or  a  tenacious  clay,  offers  the  best  protection 
against  the  air ;  and  before  the  dung  is  covered  over, 
or  as  it  were,  sealed  up,  it  should  be  dried  as  much 
as  possible.  If  the  dung  is  found  at  any  time  to 
heat  strongly,  it  should  be  turned  over,  and  cooled 
by  exposure  to  air. 

Watering  dunghills  is  sometimes  recommended 
for  checking  the  progress  of  fermentation  ;  but  this 
practice  is  inconsistent  with  just  chemical  views.  It 
may  cool  the  dung  for  a  short  time  ;  but  moisture,  as 
I  have  before  stated,  is  a  principal  agent  in  all  proces- 
ses of  decomposition.  Dry  fibrous  matter  will  never 
ferment.  Water  is  as  necessary  as  air  to  the  process  ; 
and  to  supply  it  to  fermenting  dung,  is  to  supply  an. 
agent  which  will  hasten  its  decay. 

In  all  cases  when  dung  is  fermenting,  there  are 
simple  tests  by  which  the  rapidity  of  the  process,  and 
consequently  the  injury  done,  may  be  discovered. 

If  a  thermometer  plungedinto  the  dung  does  not 
rise  to  above  100®  degrees  of  Fahrenheit,  there  is  little 
danger  of  much  aeriform  matter  flying  off.  If  the 
temperature  is  higher,  the  dung  should  be  immediate- 
ly spread  abroad. 

When  a  piece  of  paper  moistened  in  muriatic 
acid  held  over  the  steams  arising  from  a  dunghill 
gives  dense  fumes,  it  is  a  certain  test,  that  the  decom- 

N  2 


C  274  ] 

position  is  going  too  far  ;  for  this  indicates  that  vola- 
tile alkali  is  disengaged. 

When  dung  is  to  be  preserved  for  any  time,  the 
situation  in  which  it  is  kept  is  of  importance.  It 
should,  if  possible,  be  defended  from  the  sun.  To 
preserve  it  under  sheds  would  be  of  great  use ;  or  to 
make  the  site  ®f  a  dunghill  on  the  north  side  of  a  wall. 
The  floor  on  which  the  dung  is  heaped,  should,  if  pos- 
sible, be  paved  with  flat  stones  ;  and  there  should  be 
a  little  inclination  from  each  side  towards  the  centre, 
in  which  there  should  be  drains  connected  with  a 
small  well  furnished  with  a  pump,  by  which  any  fluid 
matter  may  be  collected  for  the  use  of  the  land.  It 
too  often  happens  that  a  dense  mucilaginous  and  ex- 
tractive  fluid  is  suffered  to  drain  away  from  the  dung- 
hill, so  as  to  be  entirely  lost  to  the  farm. 

Street  and  road  dung^  and  the  sweepings  of  houses 
may  be  all  regarded  as  composite  manures,  the  con- 
stitution of  them  is  necessarily  various,  as  they  are 
derived  from  a  number  of  different  substances.  These 
manures  are  usually  applied  in  a  proper  maimer,  with- 
out being  fermented. 

Soot^  which  is  principally  formed  from  the  com- 
bustion of  pit  coal  or  coal,  generally  contains  likewise 
substances  derived  from  animal  matters.  This  is  a 
very  powerful  manure.  It  affords  ammoniacal  salts 
by  distillation,  and  yields  a  brown  extract  to  hot  wa- 
ter, of  a  bitter  taste.  It  likewise  contains  an  empy- 
reumatic  oil.  Its  great  basis  is  charcoal,  in  a  state  in 
which  it  is  capable  of  being  rendered  soluble  by  the 
action  of  oxygene  and  water. 


C         '275         ] 

This  manure  is  well  fitted  to  be  used  in  the  dry* 
state,  thrown  into  the  ground  with  the  seed,  and  re- 
quires no  preparation. 

The  doctrine  of  the  proper  application  of  ma- 
nures from  organized  substances,  offers  an  illustration 
of  an  important  part  of  the  oeconomy  of  nature,  and 
of  the  happy  order  in  which  it  is  arranged. 

The  death  and  decay  of  animal  substances  tend 
to  resolve  organised  forms  into  chemical  constituents  ; 
and  the  pernicious  effluvia  disengaged  in  the  process 
seem  to  point  out  the  propriety  of  burying  them  in 
the  soil,  where  they  are  fitted  to  become  the  food  of 
vegetables.  The  fermentation  and  putrefaction  of  or- 
ganised substances  in  the  free  atmosphere  are  noxious 
processes  ;  beneath  the  surface  of  the  ground  they 
are  salutary  operations.  In  this  case  the  food  of  plants 
is  prepared  where  it  can  be  used ;  and  that  which 
would  offend  the  senses  and  injure  the  health,  if  ex- 
posed, is  converted  by  gradual  processes  info  forms  of 
beauty  and  of  usefulness  ;  the  foetid  gas  is  rendered  a 
constituent  of  the  aroma  of  the  flower,  and  what 
might  be  poison,  becomes  nourishment  to  animals 
and  to  man. 


[         276         3 


ILECTURE  VII. 

On  Manures  of  mineral  Origin^  or  fossile  Manures  ; 
their  Preparation^  and  the  Manner  in  which  they 
Act,  Of  Lime  in  its  differ eitt  States  ;  Operation  of 
Lime  as  a  Manure  and  a  Cement  ;  different  Combin- 
ations of  Lime.  Of  Gypsum  ;  Ideas  respecting  its 
Use  Of  other  Neutro-s aline  Compounds^  employed  as 
Manures.  Of  Alkalies  and  alkaline  Salts  ;  of  Com- 
mon Salt. 

THE  whole  tenor  of  the  preceding  Lectures 
shews,  that  a  great  variety  of  substances  contributes 
to  the  growth  of  plants,  and  supplies  the  materials  of 
their  nourishment.  The  conversion  of  matter  that 
has  belonged  to  living  structures  into  organised 
forms,  is  a  process  that  can  be  easily  understood ;  but 
it  is  more  difficult  to  follow  those  operations  by  which 
earthy  and  saline  matters  are  consolidated  in  the  fibre 
of  plants,  and  by  which  they  are  made  subservient  to 
their  functions.  Some  enquirers  adopting  that  sublime 
generalization  of  the  ancient  philosophers,  that  matter 
is  the  same  in  essence,  and  that  the  different  substan- 
ces considered  as  elements  by  chemists,  are  merely 
different  arrangements  of  the  same  indestructible  par- 
ticles, have  endeavoured  to  prove  that  all  the  varieties 
of  the  principles  found  in  plants,  may  be  formed  from 


[  277         ] 

the  substances  in  the  atmosphere  ;  and  that  vegetable 
life  is  a  process  in  which  bodies  that  the  analytical  phi- 
losopher is  unable  to  change  or  to  form,  are  constantly 
composed  and  decomposed.  These  opinions  have  not 
been  advanced  merely  as  hypotheses;  attempts  have 
been  made  to  support  them  by  experiments.  M. 
Schrader  and  Mr.  Braconnot.  from  a  series  of  distinct 
investigations,  have  arrived  at  the  same  conclusions. 
They  state  that  different  seeds  sown  in  fine  sand,  sul- 
phur, .  and  metallic  oxides,  and  supplied  only  with 
atmospherical  air  and  water,  produced  healthy  plants, 
which  by  analysis  yielded  various  earthy  and  saline 
matters,  which  either  were  not  contained  in  the  seeds, 
or  the  material  in  which  they  grew;  or  which  were 
contained  only  in  much  smaller  quantities  in  the  seeds: 
and  hence  they  conclude  that  they  must  have  been 
formed  from  air  or  water,  in  consequence  of  the  agen- 
cies of  the  living  organs  of  the  plant. 

The  researches  of  these  two  gentlemen  were  con- 
ducted with  much  ingenuity  and  address;  but  there 
were  circumstances  which  interfered  with  their  re- 
sults, which  they  could  not  have  known,  as  at  the 
time  their  labours  were  published  they  had  not  been 
investigated. 

I  have  found  that  common  distilled  water  is  far 
from  being  free  from  saline  impregnations.  In  analy- 
sing it  by  Voltaic  electricity,  I  procured  from  it  alkal- 
ies and  earths;  and  many  of  the  combinations  of  me- 
tals with  chlorine  are  extremely  volatile  substances. — 
When  distilled  water  is  supplied  in  an  unlimited  man- 
ner to  plants,  it  may  furnish  to  them  a  number  of  dif- 


L  278  J 

ferent  substances,  which  though  in  quantities  scarcely 
perceptible  in  the  water,  may  accumulate  in  the  plant, 
which  probably  perspires  only  absolutely  pure  water. 

In  1801  I  made  an  experiment  on  the  growth  of 
oats,  supplied  Vith  a  limited  quantity  of  distilled  wa- 
ter in  a  soil  composed  of  pure  carbonate  of  lime.  The 
soil  and  the  water  were  placed  in  a  vessel  of  iron, 
which  was  included  in  a  large  jar,  connected  with  the 
free  atmosphere  by  a  tube,  so  curved  as  to  prevent  the 
possibility  of  any  dust,  or  fluid,  or  solid  matter  from 
entering  into  the  jar.  My  object  was  to  ascertain 
whether  any  siliceous  earth  would  be  formed  in  the 
process  of  vegetation;  but  the  oats  grew  very  feebly, 
and  began  to  be  yellow  before  any  flowers  formed: 
the  entire  plants  were  burnt,  and  their  ashes  compar- 
ed with  those  from  an  equal  number  of  grains  of  oat. 
Less  siliceous  earth  was  given  by  the  plants  than  by 
the  grains;  but  their  ashes  yielded  much  more  carbon- 
ate of  lime.  That  there  was  less  siliceous  earth  I 
attribute  to  the  circumstance  of  the  husk  of  the  oat  be- 
ing thrown  off  in  germination;  and  this  is  the  part 
which  most  abounds  in  silica.  Healthy  green  oats  ta- 
ken from  a  growing  crop,  in  a  field  of  which  the  soil 
was  a  fine  sand,  yielded  siliceous  earth  in  a  much 
greater  proportion  than  an  equal  weight  of  the  corn 
artificially  raised. 

The  general  results  of  this  experiment  are  very 
much  opposed  to  the  idea  of  the  composition  of  the 
earths,  by  plants,  from  any  of  the  elements  found  in 
the  atmosphere,  or  in  water;  and  there  are  other  facts 
contrary  to  the  idea.     Jacquin  states  that  the  ashes  of 


[         279         3 

Glass  Wort  (Salsola  Soda^J  when  it  grows  in  inland 
situations,  afford  the  vegetable  alkali;  when  it  grows 
on  the  sea  shore  where  compounds  which  afford  the 
fossile  or  marine  alkali  are  more  abundant,  it  yields 
that  substance.  Du  Hamel  found,  that  plants  which 
usually  grow  on  the  sea  shore,  made  small  progress 
when  planted  in  soils  containing  little  common  salt* 
The  sunflower,  when  growing  in  lands  containing  no 
nitre,  does  not  afford  that  substance;  though  when 
watered  by  a  solution  of  nitre,  it  yields  nitre  abundant- 
ly. The  tables  of  de  Saussure,  referred  to  in  the 
Third  Lecture,  shew  th^t  the  ashes  of  plants  are  simi- 
lar in  constitution  to  the  soils  in  which  they  have 
vegetated. 

De  Saussure  made  plants  grow  in  solutions  of 
different  salts,  and  he  ascertained,  that  in  all  cases, 
certain  portions  of  the  salts  were  absorbed  by  the 
plant  and  found  unaltered  in  their  organs. 

Even  animals  do  not  appear  to  possess  the 
power  of  forming  the  alkaline  and  earthy  substan- 
ces. Dr.  Fordyce  found,  that  when  canary  birds 
at  the  time  they  were  laying  eggs  were  deprived  of 
access  to  carbonate  of  lime,  their  eggs  had  soft  shells; 
and  if  there  is, any  process  for  which  nature  may  be 
conceived  most  likely  to  supply  resources  of  this  kind, 
it  is  that  connected  with  the  reproduction  of  the  spe* 
cies. 

As  the  evidence  on  the  subject  now  stands,  it 
seems  fair  to  conclude  that  the  different  earths  and 
saline  substances  found  in  the  organs  of  plants,  are 
-supplied  by  the  soils  in  which  they  grow;  and  in  no 


[  280  J 

cases  composed  by  new  arrangements  of  the  elements 
in  air  dr  water.  What  may  be  our  ultimate  view  of 
the  laws  of  chemistry,  or  how  far  our  ideas  of  element- 
ary principles  may  be  simplified,  it  is  impossible  to  say. 
We  can  only  reason  from  facis.  We  cannot  imitate 
the  powers  of  composition  belonging  to  vegetable 
structures;  but  at  least  we  can  understand  them:  and 
as  far  as  our  researches  have  gone,  it  appears  that  in 
vegetation  compound  forms  are  uniformly  produced 
from  simpler  ones;  and  elements  in  the  soil,  ,the  at- 
mosphere, and  the  earth  absorbed  and  made  parts  of 
beautiful  diversified  structures. 

The  views  which  have  been  just  developed  lead 
to  correct  ideas  of  the  operation  of  these  manures 
which  are  not  necessarily  the  result  of  decayed  organi- 
zed bodies,  and  which  are  not  composed  of  different 
proportions  of  carbon,  hydrogene,  oxygene  and  azote. 
— They  must  produce  their  effect,  either  by  becom- 
ing  a  constituent  part  of  the  plant,  or  by  acting  upon 
its  more  essential  food,  so  as  to  render  it  more  fitted 
for  the  purposes  of  vegetable  life. 

The  only  substances  which  can  with  propriety  be 
called  fossils  manures,  and  which  are  found  unmixed 
with  the  remains  of  any  organized  beings,  are  certain 
alkaline  earths  or  alkalies,  and  their  combinations. 

The  only  alkaline  earths  which  have  been  hither- 
to applied  in  this  way,  are  lime  and  magnesia.  Potassa 
and  soda,  the  two  fixed  alkalies,  are  both  used  in 
certain  of  their  chemical  compounds.  I  shall  state  in 
succession  such  facts  as  have  come  to  my  knowledge 
respecting  each  of  these  bodies  in  their  applications  to 


C  281  J 

the  purposes  of  agriculture ;  but  I  shall  enlarge  most 
upon  the  subject  of  lime  ;  and  if  I  should  enter  into 
some  details  which  may  be  tedious  and  minute,  I  trust, 
my  excuse  will  be  found  in  the  importance  of  the  en- 
quiry ;  and  it  is  one  which  has  been  greatly  elucidated 
by  late  discoveries. 

The  most  common  form  In  which  lime  is  found 
on  the  surface  of  the  earth,  is  in  a  state  of  combination 
with  carbonic  acid  or  fixed  air.  If  a  piece  of  lime- 
stone, or  chalk,  be  thrown  into  a  fluid  acid,  there  will 
be  an  effervescence.  This  is  owing  to  the  escape  of 
the  carbonic  acid  gas.  The  lime  becomes  dissolved 
in  the  liquor. 

When  limestone  is  strongly  heated,  the  car- 
bonic acid  gas  is  expelled,  and  then  nothing  remains 
but  the  pure  alkaline  earth  ;  in  this  case  there  is  a  loss 
of  weight ;  and  of  if  the  fire  has  been  very  high,  it 
approaches  to  one-half  the  weight  of  the  stone ;  but, 
in  common  cases  limestones,  if  well  dried  before  burn- 
ing, do  not  lose  much  more  than  from  35  to  40  per 
cent.,  or  from  seven  to  eight  parts  out  of  20. 

I  mentioned  in  discussing  the  agencies  of  the  at- 
mosphere upon  vegetables,  in  the  beginning  of  the  Fifth 
Lecture,  that  air  always  contains  carbonic  acid  gas,  and 
that  lime  is  precipitated  from  water  by  this  substance. 
When  burnt  lime  is  exposed  to  the  atmosphere,  in  a 
certain  time  it  becomes  mild  and  is  the  same  substance 
as  that  precipitated  from  lime  water ;  it  is  combined 
with  carbonic  acid  gas.  Quicklime;  when  first  made, 
is  caustic  and  burning  to  the  tongue,  renders  vegetable 
blues  green,  and  is  soluble  in  water  ;  but  when  com- 

o  2 


L  282  J 

bincd  with  carbonic  acid  it  loses  all  these  properties, 
its  solubility  and  its  taste :  it  regains  its  power  of  ef- 
fervescing, and  becomes  the  same  chemical  substance 
as  chalk  or  limestone. 

Very  few  limestones  or  chalks  consist  entirely  of 
lime  and  carbonic  acid.  The  statuary  marbles,  or 
certain  of  the  rhomboidal  spars,  are  almost  the  only 
pure  species  ;  and  the  different  properties  of  limestone 
both  as  manures  and  cements,  depend  upon  the  nature 
of  the  ingredients  mixed  in  the  limestone ;  for  the 
true  calcareous  element,  the  carbonate  of  Hme,  is  uni- 
formly the  same  in  nature,  properties  and  effects,  and 
consist  of  one  proportion  of  carbonic  acid  41.4,  and 
one  of  lime  55, 

When  a  limestone  does  not  copiously  effervesce 
in  acids,  and  is  sufficiently  hard  to  scratch  glass,  it 
contains  silicious  and  probably  aluminous  earth. 
When  it  is  deep  brown  or  red,  or  strongly  coloured 
of  any  of  the  shades  of  brown  or  yellow,  it  contains 
oxide  of  iron.  When  it  is  not  sufficiently  hard  to 
scratch  glass,  but  effervesces  slowly,  and  makes  the 
acid  in  which  it  effervesces  milky,  it  contains  mag- 
nesia. And  when  it  is  black  and  emits  a  foetid  smell 
if  rubbed,  it  contains  coally  or  bituminous  matter. 

The  analysis  of  limestones  is  not  a  difficult  mat- 
ter ;  and  the  proportions  of  their  constituent  parts 
may  be  easily  ascertained,  by  the  processes  described 
in  the  Lecture  on  the  Analysis  of  Soils  ;  and  usually 
with  sufficient  accuracy  for  all  the  purposes  of  the 
farmer,  by  the  fifth  process. 

Before  any  opinion  can  be  formed  of  the  man- 
ner in  which  the  different  ingredients  in  limestones 


[  2S3  j 

modify  their  properties,  it  will  be  necessary  to  consi- 
der the  operation  of  the  pure  calcareous  element  as  a 
manure,  and  as  a  cement. 

Quicklime  in  its  pure  state,  whether  in  powder 
or  dissolved  in  water,  is  injurious  to  plants. — I  have 
in  several  instances  killed  grass  by  watering  it  with 
lime  water. — But  lime  in  its  state  of  combination  with 
carbonic  acid,  as  is  evident  from  the  analyses  given  in 
the  Fourth  Lecture,  is  a  useful  ingredient  in  soils. 
Calcareous  earth  is  found  in  the  ashes  of  the  greater 
number  of  plants  ;  and  exposed  to  the  air,  lime  can- 
not long  continue  caustic,  for  the  reasons  that  were 
just  now  assigned  5  but  soon  becomes  united  to  car- 
bonic acid.  : 

When  newly  burnt  lime  is  exposed  to  air,  it  soon 
falls  into  powder ;  in  this  case  it  it  called  slacked 
lime ;  and  the  same  effect  is  immediately  produced 
by  throwing  water  upon  it,  when  it  heats  violently, 
and  the  water  disappears. 

Slacked  lime  is  merely  a  Combination  of  lime, 
v/ith  about  one-third  of  its  weight  of  water  j  i.  e.  55 
parts  of  lime  absorb  1 7  parts  of  water ;  and  in  this 
case  It  is  composed  of  a  definite  proportion  of  lime  to 
a  definite  proportion  of  water,  and  is  called  by  che- 
mists hydrate  of  lime  ;  and  when  hydrate  of  lime  be- 
comes carbonate  of  lime  by  long  exposure  to  air,  the 
water  is  expelled,  and  the  carbonic  acid  gas  takes  its 
place. 

When  lime,  whether  freshly  burnt  or  slacked,  is 
mixed  with  any  moist  fibrous  vegetable  matter,  there 
is  a  strong  action  between  the  lime  and  the  vegetable 


[  2S4  ] 

matter,  and  they  form  a  kind  of  compost  together, 
of  which  a  part  is  usually  soluble  in  water- 
By  this  kind  of  operation,  lime  renders  matter 
which  was  before  comparatively  inert,  nutritive  ;  and 
as  charcoal  and  oxygene  abound  in  all  vegetable  mat- 
ters, it  becomes  at  the  same  time  converted  into  car- 
bonate of  lime. 

Mild  lime,  powdered  limestone,  marles  or  chalks, 
have  no  action  of  this  kind  upon  vegetable  matter ; 
by  their  action  they  prevent  the  too  rapid  decomposi- 
tion of  substances  already  dissolved ;  but  they  have  no 
tendency  to  form  soluble  matters. 

It  is  obvious  from  these  circumstances,  that  the 
operation  of  quicklime,  and  marie  or  chalk,  depends 
upon  principles  altogether  different. — Quicklime  in 
being  applied  to  land  tends  to  bring  any  hard  vegeta- 
ble matter  that  it  contains  into  a  state  of  more  rapid 
decomposition  and  solution,  so  as  to  render  it  a  pro- 
per food  for  plants.— Chalk,  and  marie,  or  carbonate 
of  lime  will  only  improve  the  texture  of  the  soil,  or 
its  relation  to  absorption  ;  it  acts  merely  as  one  of  its 
earthy  ingredients. — Quicklime,  when  it  becomes 
mild,  operates  in  the  same  manner  as  chalk ;  but  in 
the  act  of  becoming  mild,  it  prepares  soluble  out  of 
insoluble  matter. 

It  is  upon  this  circumstance  that  the  operation  of 
lime  in  the  preparation  for  wheat  crops  depends  ;  and 
its  efficacy  in  fertilizing  peats,  and  in  bringing  into  a 
state  of  cultivation  all  soils  abounding  in  hard  roots, 
or  dry  fibres,  or  inert  vegetable  matter. 

The  solution  of  the  question  whether  quicklime 
ought  to  be  applied  to  a  soil,  depends  upon  the  quan. 


[  285  ] 

tity  of  inert  vegetable  matter  that  it  contains.  The 
solution  of  the  question  whether  marie,  mild  lime,  or 
powdered  limestone  ought  to  be  applied,  depends  upon 
the  quantity  of  calcareous  matter  already  in  the  soil. 
All  soils  are  improved  by  mild  lime,  and  ultimately 
by  quicklime  which  do  not  effervesce  with  acids  5  and 
sands  more  than  clays. 

When  a  soil  deficient  in  calcareous  matter  contains 
much  soluble  vegetable  manure,  the  application  of 
quicklime  should  always  be  avoided,  as  it  either  tends 
to  decompose  the  soluble  matters  by  uniting  to  their 
carbon  and  oxygene  so  as  to  become  mild  lime,  or  it 
combines  with  the  soluble  matters,  and  forms  com- 
pounds having  less  attraction  for  water  than  the  pure 
vegetable  substance. 

The  case  is  the  same  with  respect  to  most  animal 
manures ;  but  the  operation  of  the  lime  is  different  in  difr 
ferent  cases,  and  depends  upon  the  nature  of  the  animal 
matter.  Lime  forms  a  kind  of  insoluble  soap  with  oily 
matters,  and  then  gradually  decomposes  them  by  se- 
parating from  them  oxygene  and  carbon.  It  combines 
likewise  with  the  animal  acids  ;  and  probably  assists 
their  decomposition  by  abstracting  carbonaceous  mat- 
ter from  them  combined  with  oxygene  ;  and  conse- 
quently it  must  render  them  less  nutritive.  It  tends  to 
diminish  likewise  the  nutritive  powers  of  albumen  from 
the  same  causes  ;  and  always  destroys  to  a  certain 
extent  the  efficacy  of  animal  manures,  either  by  com- 
bining with  certain  of  their  elements,  or  by  giving  to 
them  new  arrangements.  Lime  should  never  be  ap- 
plied with  animal  manures,  unless  they  are  too  rich. 


C  286  ] 

or  for  the  purpose  of  preventing  noxious  effluvia,  as 
in  certain  cases  mentioned  in  the  last  Lecture.  It  it 
injurious  when  mixed  with  any  common  dung,  and 
tends  to  render  the  extractive  matter  insoluble. 

I  made  an  experiment  on  this  subject :  I  mixed 
a  quantity  of  the  brown  soluble  extract,  which  was 
procured  from  sheeps'  dung  with  five  times  its  weight 
of  quicklime.  I  then  moistened  them  with  water ; 
the  mixture  heated  very  much  ;  it  was  suffered  to  re- 
main for  14  hours,  and  was  then  acted  on  by  six  or 
seven  times  its  bulk  of  pure  water :  the  water,  after 
being  passed  through  a  filter,  was  evaporated  to  dry- 
ness ;  the  solid  matter  obtained  was  scarcely  coloured, 
and  was  lime  mixed  with  a  little  saline  matter. 

In  those  cases  in  which  fermentation  is  useful  to 
produce  nutriment  from  vegetable  substances,  lime  is 
always  efficacious.  I  mixed  some  moist  tanner's  spent 
bark  with  one-fifth  of  its  weight  of  quicklime,  and  suf- 
fered them  to  remain  together  in  a  close  vessel  for 
three  months  ;  the  lime  had  become  coloured  and  was 
effervescent :  when  water  was  boiled  upon  the  mix- 
ture it  gained  a  tint  of  fawn  colour,  and  by  evapora- 
tion furnished  a  fawn-coloured  powder,  which  must 
have  consisted  of  lime  united  to  vegetable  matter,  for 
it  burnt  when  stongly  heated  and  left  a  residuum  of 
mild  lime. 

The  limestones  containing  alumina  and  silica  are 
less  fitted  for  the  purposes  of  manure  than  pure  lime- 
stones ;  but  the  Hme  formed  from  them  has  no  nox- 
ious  quality.  Such  stones  are  less  efficacious,  merely 
because  they  furnish  a  smaller  quantity  of  quicklime. 


[  287  3 

I  mentioned  bituminous  limestones.  There  is 
very  seldom  any  considerable  portion  of  coally  matter 
in  these  stones  ;  never  as  much  as  five  parts  in  100  ; 
but  such  limestones  make  very  good  lime.  The  car- 
bonaceous matter  can  do  no  injury  to  the  land,  and 
may,  under  certain  circumstances,  become  a  food  of 
the  plant,  as  is  evident  from  what  was  stated  in  the 
last  Lecture. 

The  subject  of  the  application  of  the  magnesian 
limestone  is  one  of  great  interest. 

It  had  been  long  known  to  farmers  in  the  neigh- 
bourhood of  Doncaster,  that  lime  made  from  a  certain 
limestone  applied  to  the  land,  often  injured  the  crops 
considerably,  as  I  mentioned  in  the  Introductory  Lec- 
ture. Mr.  Tennant,  in  making  a  scries  of  experi- 
ments upon  this  peculiar  calcareous  substance,  found 
that  it  contained  magnesia ;  and  on  mixing  some  cal- 
cined magnesia  with  soil,  in  which  he  sowed  different 
seeds,  he  found  that  they  either  died,  or  vegetated  in 
a  very  imperfect  manner,  and  the  plants  were  never 
healthy.  And  with  great  justice  and  ingenuity  he  re- 
ferred the  bad  effects  of  the  peculiar  limestone  to  the 
magnesian  earth  it  contains. 

In  making  some  enquiries  concerning  this  sub- 
ject, I  found  that  there  were  cases  in  which  this  mag- 
nesian limestone  was  used  with  good  effect. 

Amongst  some  specimens  of  limestone  which 
Lord  Somerville  put  into  my  hands,  two  marked  as 
peculiarly  good  proved  to  be  magnesian  limestones. 
And  lime  made  from  the  Breedon  limestone  is  used  in 
Leicestershire,  where  it  is  called  hot  lime  ;  and  I  have 


[  283  J 

been  informed  by  farmers  in  the  neighbourhood  of  the 
quarry,  that  they  employ  it  advantageously  in  small 
quantities,  seldom  more  than  25  or  30  bushels  to  the 
acre.  And  that  they  find  it  may  be  used  with  good 
effect  in  larger  quantities  upon  rich  land. 

A  minute  chemical  consideration  of  this  question 
will  lead  to  its  solution. 

Magnesia  has  a  much  weaker  attraction  for  car- 
bonic acid  than  lime,  and  will  remain  in  the  state  of 
caustic  or  calcined  magnesia  for  many  months,  though 
exposed  to  the  air.  And  as  long  as  any  caustic  lime 
remains,  the  magnesia  cannot  be  combined  with  car- 
bonic acid,  for  lime  instantly  attracts  carbonic  acid 
from  magnesia. 

When  a  magnesian  limestone  is  burnt,  the  mag- 
nesia is  deprived  of  carbonic  acid  much  sooner  than 
the  lime ;  and  if  there  is  not  much  vegetable  or  ani- 
mal matter  in  the  soil  to  supply  by  its  decomposition 
carbonic  acid,  the  magnesia  will  remain  for  a  long 
while  in  the  caustic  state ;  and  in  this  state  acts  as  a 
poison  to  certain  vegetables.  And  that  more  magne- 
sian lime  may  be  used  upon  rich  soils,  seems  to  be 
owing  to  the  circumstance,  that  the  decomposition  of 
the  manure  in  them  supplies  carbonic  acid.  And 
magnesia  in  its  mild  state,  i,  e.  fully  combined  with 
carbonic  acid,  seems  to  be  always  an  useful  constituent 
of  soils.  I  have  thrown  carbonate  of  magnesia  (pro- 
cured by  boiling  the  solution  of  magnesia  in  super- 
carbonate  of  potassa)  upon  grass,  and  upon  growing 
wheat  and  barley,  so  as  to  render  the  surface  white  ; 
but  the  vegetation  was  not  injured  in  the  slightest  de- 


[  289  ]         ■ 

gree.  And  one  of  ihe  most  fertile  parts  cf  Cornwall, 
the  Lizard,  is  a  district  in  which  the  soil  contains 
mild  magnesian  earth. 

The  Lizard  Downs  bear  a  short  and  green  grass, 
which  feeds  sheep  producing  excellent  mutton  ;  and 
the  cultivated  parts  are  amongst  the  best  corn  lands  in 
the  county. 

That  the  theory  which  I  have  ventured  to  give  of 
the  operation  of  magnesian  lime  is  not  unfounded,  is 
shewn  by  an  experiment  which  I  made  expressly  for 
the  purpose  of  determining  the  true  nature  of  the 
operation  of  this  substance.  I  took  four  portions  of 
the  same  soil :  with  one  I  mixed  20  of  its  weight  of 
caustic  magnesia,  wath  another  I  mixed  the  same 
quantity  of  magnesia  and  a  proportion  of  a  fat  decom- 
posing peat  equal  to  one-fourth  of  the  weight  of  the 
soil.  One  portion  of  soil  remained  in  its  natural 
state  :  and  another  was  mixed  with  peat  without  mag- 
nesia. The  mixtures  were  made  in  December  1 806  ; 
and  in  April  1807,  barley  was  sown  in  all  of  them. 
It  grew  very  well  in  the  pure  soil ;  but  better  in  the 
soil  containing  the  magnesia  and  peat ;  and  nearly  as 
well  in  the  soil  containing  peat  alone  :  but  in  the  soil 
containing  the  magnesia  alone,  it  rose  very  feeble,  and 
looked  yellow  and  sickly. 

I  repeated  this  experiment  in  the  summer  of  1810 
with  similar  results  ;  and  I  found  that  the  magnesia 
in  the  soil  mixed  with  peat  became  strongly  efferves- 
cent, whilst  the  portion  in  the  unmixed  soil  gave  car- 
bonic acid  in  much  smaller  quantities.  In  the  one  case 
the  magnesia  had  assisted  in  the  formation  of  a  man^ 

p2 


[         290         3 

ute,  and  had  become  mild  5  in  the  otner  case  it  had 
acted  as  a  poison. 

It  is  obvious  from  what  has  been  said  that  lime 
from  the  magnesian  limestone  may  be  applied  in  large 
quantities  to  pea'ts;  and  that  where  lands  have  been 
injured  by  the  application  of  too  large  a  quantity  of 
magnesian  lime,  peat  will  be  a  proper  and  efficient 
remedy. 

I  mentioned  that  magnesian  lime  stones  efferves- 
ced little  when  plunged  into  an  acid.  A  simple  test 
of  magnesia  in  a  limestone  is  this  circumstance,  in  its 
rendering  diluted  nitric  acid,  or  acqua  fortis  milky. 

From  the  analysis  of  Mr.  Tennant,  it  appears 
that  the  magnesian  limestones  contain  from 

20.3  to  22.5  magnesia. 

29.5  to  31.7  lime. 

47.2  carbonic  acid. 
0.8  clay  and  oxide  of  iron. 
Magnesian  limestones  are  usually  coloured  brown 
or  pale  yellow,  they  are  found  in  Somersetshire,  Lei- 
cestershire, Derbyshire,  Shropshire,  Durham,  and 
Yorkshire.  I  have  never  met  with  any  in  other  coun- 
ties in  England;  but  they  abound  in  many  parts  of 
Ireland,  particularly  near  Belfast.  ' 

The  use  of  lime  as  a  cement  is  not  a  proper  sub- 
ject for  extensive  discussion  in  a  course  of  Lectures  on 
the  chemistry  of  agriculture;  yet  as  the  theory  of  the 
operation  of  lime  in  this  way  is  not  fully  stated  in  any 
elementary  book  that  I  have  perused,  I  shall  say  a 
very  few  words  on  the  applications  of  this  part  of  che- 
mical  knowledge. 


C         291         3 

There  are  two  modes  in  which  lime  acts  as  a  ce- 
ment; in  its  combination  with  water,  and  in  its  combi- 
nation with  carbonic  acid. 

The  hydrate  of  lime  has  been  already  mentioned. 
When  quick  lime  is  rapidly  made  into  a  paste  with 
water,  it  soon  loses  its  softness,  and  the  water  and  the 
lime  form  together  a  solid  coherent  mass,  which  con- 
sists, as  has  been  stated  before,  of  1 7  parts  of  water  to 
55  parts  of  lime.  When  hydrate  of  lime  whilst  it  is 
consolidating  is  mixed  with  red  oxide  of  iron,  alumina^ 
or  silica,  the  mixture  becomes  harder  and  more  co- 
herent than  when  lime  alone  is  used;  and  it  appears 
that  this  is  owing  to  a  certain  degree  of  chemical  at- 
traction between  hydrate  of  lime  and  these  bodies;  and 
they  render  it  less  liable  to  decompose  by  the  action 
of  the  carbonic  acid  in  the  air,  and  less  soluble  in 
water. 

The  basis  of  all  cements  that  are  used  for 
works  which  are  to  be  covered  with  water  must  be 
formed  from  hydrate  of  lime;  and  the  lime  made  from 
impure  limestones  answers  this  purpose  very  well. 
Puzzolana  is  composed  principally  ot  silica,  alumina, 
and  oxide  of  iron;  and  it  is  used  mixed  with  lime  to 
form  cements  intended  to  be  employed  under  water, 
Mr.  Smeaton,  in  the  construction  of  the  Eddystone 
light  house,  used  a  cement  composed  of  equal  parts  by^ 
weight  of  slacked  lime  and  puzzolana.  Puzzolana  is 
a  decomposed  lava.  Tarras,  which  was  formerly  im- 
ported in  considerable  quantities  from  Holland,  is  a 
mere  decomposed  basalt:  two  parts  of  slacked  lime  and 
one  part  of  tarras  forms  the  principal  part  of  the  mor- 


[         292         ] 

tar  used  in  the  great  dykes  of  Holland.  Substances 
which  will  answer  all  the  ends  of  puzzolana  and  tar- 
ras  are  abundant  in  the  British  islands.  An  excellent 
red  tarras  may  be  procured  in  any  quantities  from  the 
Giants'  Causeway  in  the  north  of  Ireland:  and  decom- 
posing basalt  is  abundant  in  many  parts  of  Scotland, 
and  in  the  northern  districts  of  England  in  which  coal 
is  found. 

Parker's  cement,  and  cements  of  the  same  kind 
made  at  the  alum  works  of  Lord  Dundas  and  Lord 
Mulgrave  are  mixtures  of  calcined  ferruginous  stones, 
with  hydrate  of  lime. 

The  cements  which  act  by  combining  with  car- 
bonic acid,  or  the  common  mortars,  are  made  by  mix- 
ing together  slacked  Hme  and  sand.  These  mortars, 
at  first  solidify  as  hydrates,  and  are  slowly  converted 
into  carbonate  of  lime  by  the  action  of  the  carbonic 
acid  of  the  air.  Mr.  Tennant,  found  that  a  mortar  of 
this  kind  in  three  years  and  a  quarter  had  regained  63 
per  cent,  of  the  quantity  of  carbonic  gas  which  con- 
stitutes the  definite  proportion  in  carbonate  of  lime. 
The  rubbish  of  mortar  from  houses  owes  its  power  to 
benefit  lands  principally  to  the  carbonate  of  lime  it 
contains;  and  the  sand  in  it;  and  its  state  of  cohesion 
renders  it  particularly  fitted  to  improve  clayey  soils. 

The  hardness  of  the  mortar  in  very  old  buildings 
depends  upon  the  perfect  conversion  of  all  its  parts 
into  carbonate  of  lime.  The  purest  limestones  are  the 
best  adapted  for  making  this  kind  of  mortar;  the  mag- 
nesian  limestones  make  excellent  water  cements;  but 
act  with  too  /ittle  energy  upon  carbonic  acid  gas  to 
make  good  common  morter. 


i:         293         ] 

The  Romans,  according  to  Pliny,  made  their 
best  mortar  a  year  before  it  was  used;  so  that  it  was 
partially  combined  with  carbonic  acid  gas  before  it 
was  employed. 

In  burning  lime  there  are  some  particular  pre- 
cautions required  for  the  different  kinds  of  limestones. 
In  general,  one  bushel  of  coal  is  sufficient  to  make 
four  or  five  bushels  of  lime.  The  magnesian  lime- 
stone requires  less  fuel  than  the  common  limestone. 
In  all  cases  in  which  a  limestone  containing  much  alu- 
minous or  siliceous  earth  is  burnt,  great  care  should 
be  taken  to  prevent  the  fire  from  becoming  too  intense; 
for  such  lime  easily  virtrifies,  in  consequence  of  the 
affinity  of  lime  for  silica  and  alumina.  And  as  in  some 
J^laces  there  are  no  other  limestones  than  such  as  con- 
tain other  earths,  it  is  important  to  attend  to  this  cir- 
cumstance. A  moderately  good  lime  may  be  made  at 
a  low  red  heat;  but  it  will  melt  into  a  glass  at  a  white 
heat.  In  limekilns  for  burning  such  lime,  there 
should  be  always  a  damper. 

In  general,  when  limestones  are  not  magnesian 
their  purity  will  be  indicated  by  their  loss  of  weight 
in  burning;  the  more  they  lose  the  larger  is  the  quan- 
tity of  calcareous  matter  they  contain.  The  magne- 
sian limestones  contain  more  carbonic  acid  than  the 
common  limestones;  and  I  have  found  all  of  them  lose 
more  than  half  their  weight  by  calcination. 

Besides  being  used  in  the  forms  of  lime  and  carbon- 
ate of  lime,   calcareous  matter  is  applied  for  the  pur- 
poses of  agriculture  in  other  combinations.      One  of  ' 
these  bodies  is  gypsum  or  sulphate  of  lime.    This  sub- 


L         ^-^94         j 

stance  consists  of  sulphuric  acid  (the  sams  body  that 
exists  combined  with  water  in  oil  of  vitriol)  and  lime; 
and  when  dry  it  is  composed  of  55  parts  of  lime  and  75 
parts  of  sulphuric  acid.  Common  gypsum  or  selenite, 
such  as  that  found  at  Shotover  hill  near  Oxford,  con- 
tains besides  sulphuric  acid  and  lime,  a  considerable 
quantity  of  water ;  and  its  composition  may  be  thus 
expressed  : 

Sulphuric  acid  one  proportion  75 

Lime  one  proportion      -         -         55 

Water  two  proportions  -         -         34 

The  nature  of  gypsum  is  easily  demonstrated  ; 

if  oil  of  vitriol  be  added  to  quicklime  there  is  a  violent 

heat  produced  ;  when  the  mixture  is  ignited,  water  is 

given  off,  and  gypsum  alone  is  the  result,  if  the  acid 

has  been  used  in  sufficient  quantity  ;    and  gypsum 

mixed  with  quicklime,  if  the  quantity  has  been  defi« 

cient.^     Gypsum  free  from  water  is  sometimes  found 

in  nature,  when  it  is  called  anhydrous  seienite.     It  is 

distinguished  from  common  gypsum  by  giving  off  no 

water  when  heated. 

When  gypsum  free  from  water,  or  deprived  of 
water  by  heat,  is  made  into  a  paste  with  water,  it  ra- 
pidly sets  by  combining  with  that  fluid.  Plaister  of 
Paris  is  powdered  dry  gypsum;  and  its  property  as  a 
cement,  and  in  its  use  in  making  casts  depends  upon 
its  solidifying  a  certain  quantity  of  water,  and  making 
with  it  a  coherent  mass.  Gypsum  is  soluble  in  about 
500  times  its  weight  of  cold  water,  and  is  more  solu- 
ble in  hot  w^ater  ;  so  that  when  water  has  been  boiled 
in  contact  with  gypsum,  crystals  of  this  substance  are 


deposited  as  the  water  cools.  Gypsum  Is  easily  dis- 
tinguished when  dissolved  by  its  properties  of  afford- 
ing precipitates  to  solutions  of  oxalates  and  of  barytic 
salts. 

Great  difference  of  opinion  has  prevailed  amongst 
agriculturists  with  respect  to  the  uses  of  gypsum.  It 
has  been  advantageously  used  in  Kent,  and  various 
testimonies  in  favour  of  its  efficacy  have  been  laid  be- 
fore the  Board  of  Agriculture  by  Mr.  Smith.  In 
America  it  is  employed  with  signal  success  ;  but  in 
most  counties  of  England  it  has  failed,  though  tried 
in  various  ways,  and  upon  different  crops. 

Very  discordant  notions  have  been  formed  as  to 
the  mode  of  operation  of  gypsum.  It  has  been  sup- 
posed by  some  persons  to  act  by  its  power  of  attract- 
ing moisture  from  the  air  ;  but  this  agency  must  be 
comparatively  insignificant.  When  combined  with  wa- 
ter it  retains  that  fluid  too  powerfully  to  yield  it  to  the 
roots  of  the  plant,  and  its  adhesive  attraction  for  mois- 
ture is  inconsiderable  ;  the  small  quantity  in  which  it 
is  used  likewise  is  a  circumstance  hostile  to  this  idea. 

It  has  been  said  that  gypsum  assists  the  putrefac- 
tion of  animal  substances,  and  the  decomposition  of 
manure.  I  have  tried  some  experiments  on  this  subject 
which  are  contradictory  to  the  notion,  I  mixed  some 
minced  veal  with  about  ih  part  of  its  weight  of  gyp- 
sum, and  exposed  some  veal  without  gypsum  under 
the  same  circumstances  :  there  was  no  difference  in 
the  time  in  which  they  began  to  putrefy  ;  and  the  pro- 
cess seemed  to  me  most  rapid  in  the  case  in  which  there 
was  no  gypsum  present.     I  made  other  similar  mix- 


[         296         ] 

tures,  employing  in  some  cases  larger,  and  in  some 
cases  smaller  quantities  of  gypsum ;  and  I  used 
pigeons'  dung  in  one  instance  instead  of  flesh,  and 
with  precisely  similar  results.  It  certainly  in  no  case 
increased  the  rapidity  of  putrefaction. 

Though  it  is  not  generally  known,  yet  a  series  of 
experiments  has  been  carried  on  for  a  great  length  of 
time  in  this  country  upon  the  operation  of  gypsum  as 
a  manure.  The  Berkshire  and  the  Wiltshire  peat- 
ashes  contain  a  considerable  portion  of  this  substance. 
In  the  Newbury  peat-ashes  I  have  found  from  one 
fourth  to  one-third  of  gypsum  ;  and  a  larger  quantity 
in  some  peat-ashes  from  the  neighbourhood  of  Stock- 
bridge  :  the  other  constituents  of  these  ashes  are  cal- 
careous, aluminous,  and  siliceous  earth,  with  variable 
quantities  of  sulphate  of  potassa,  a  little  common  salt, 
and  sometimes  oxide  of  iron.  The  red  ashes  contain 
most  of  this  last  substance. 

These  peat-ashes  are  used  as  a  top  dressing  for 
cultivated  grasses,  particularly  sainfoin  and  clover. 
In  examining  the  ashes  of  sainfoin,  clover,  and  rye 
grass,  I  found  that  they  afforded  considerable  quanti* 
ties  of  gypsum  ;  and  this  substance,  probably,  is  ind- 
mately  combined  as  a  necessary  part  of  their  woody 
fibre.  If  this  be  allowed,  it  is  easy  to  explain  the  rea- 
son why  it  operates  in  such  small  quantities  ;  for  the 
whole  of  a  clover  crop,  or  sainfoin  crop,  on  an  acre, 
according  to  my  estimation,  would  afford  by  incinera- 
tion only  three  or  four  bushels  of  gypsum.  In  exam- 
ining the  soil  in  a  field  near  Newbury,  which  was  ta-  ^ 
ken  from  below  a  foot-path  near  the  gate,  where  gyp- 


[         297         J 

sum  could  not  have  been  artificially  furnished,  I  could 
not  detect  any  of  this  substance  in  it;  and  at  the  very 
time  I  collected  the  soil,  the  peat-ashes  were  applied 
to  the  clover  in  the  field.  The  reason  why  gypsum  is 
not  generally  efficacious  is  probably  because  most 
cultivated  soils  contain  it  in  sufficient  quantities  for  the 
use  of  the  grasses.  In  the  common  course  of  cultiva- 
tion, gypsum  is  furnished  in  the  manure;  for  it  is  con- 
tained in  stable  dung,  and  in  the  dung  of  all  cattle  fed 
on  grass;  and  it  is  not  taken  up  in  corn  crops,  or  crops 
of  peas  and  beans,  and  in  very  small  quantities  in 
turnip  creeps;  but  where  lands  are  exclusively  devoted 
to  pasturage  and  hay,  it  will  be  continually  consumed. 
1  have  examined,  four  different  soils  cultivated  by  a 
series  of  common  courses  of  crops,  for  gypsum.  One 
was  alight  sand  from  Norfolk;  another  a  clay  bearing 
good  wheat  from  Middlesex;  the  third  a  sand  from 
Sussex;  the  fourth  a  clay  from  Essex.  I  found  gyp- 
sum in  all  ot  them;  and  in  the  Middlesex  soil  it  amount- 
ed nearly  to  one  per  cent.  Lord  Dundas  informs  me, 
that  having  tried  gypsum  without  any  benefit  on  two 
of  his  estates  in  Yorkshire,  he  was  induced  to  have 
the  soil  examined  for  gypsum  according  to  the  pro- 
cess described  in  the  Fourth  Lecture,  and  this  sub- 
stance was  found  in  both  the  soils. 

Should  these  statements  be  confirmed  by  future 
enquirers,  a  practical  inf  rence  of  some  value  may  be 
derived  from  them.  It  is  possible  that  lands  which 
have  ceased  to  bear  good  crops  of  clover,  or  artificial 
grasses,  may  be  restored  by  being  manured  with  gyp* 
sum.     I  have  mentioned  that  this  sub.slance  is  found 

Q2 


[  298         ] 

in  Oxfordshire;  it  is  likewise  abundant  in  many  other 
parts  of  England;  in  Gloucestershire,  Somersetshire, 
Derbyshire,  Yorkshire,  Stc.  and  requires  only  pulveri- 
zation for  its  preparation. 

Some  very  interesting  documents  upon  the  use  of 
sulphate  of  iron  or  green  vitriol,  which  is  a  salt  pro- 
duced from  peat  in  Bedfordshire,  have  been  laid  be- 
fore the  Board  by  Dr.  Pearson;  and  I  have  witnessed 
the  fertilizing  effects  of  a  ferruginous  water  used  for 
irrigating  a  grass  meadow  made  by  the  Duke  of  Man- 
chester, at  Priestley  Bog  near  Woburn,  an  account  of 
the  produce  of  which  has  been  published  by  the  Board 
of  Agriculture.  I  have  no  doubt  that  the  peat  salt 
and  the  vitriolic  water  acted  chiefly  by  producing  gyp- 
sum. 

The  soils  on  which  both  are  efficacious  are  cal- 
careous; and  sulphate  of  iron  is  decomposed  by  the 
carbonate  of  lime  in  such  soils.  The  sulphate  of  iron 
consists  of  sulphuric  acid  and  oxide  of  iron,  and  is  an 
,acid  and  a  very  soluble  salt;  when  a  solution  of  it  is 
mixed  with  carbonate  of  lime,  the  sulphuric  acid  quits 
the  oxide  of  iron  to  unite  td^the  lime,  and  the  com- 
pounds produced  are  insipid  and  comparatively  inso- 
luble. 

1  collected  some  of  the  deposition  from  the  fer- 
ruginous water  on  the  soil  in  Priestley  meadow.  I 
found  it  consisted  of  gypsum,  carbonate  of  iron,  and 
insoluble  sulphate  of  iron.  The  principal  grasses  in 
Priestley  meadow  are,  meadow  fox-tail,  cook's-foot, 
meadow  fescue,  fiorin,  and  sweet  scented  vernal  grass. 
I  have  examined  the  ashes  of  three  of  the  grasses. 


[  299         ] 

meadow  fox-tail,  cook's-foot,  and  fiorin.     They  con- 
tained a  considerable  proportion  of  gypsum. 

Vitriolic  impregnations  in  soils  where  there  is  no 
calcareous  matter,  as  in  a  soil  from  Lincolnshire,  to 
which  I  referred  in  the  Fourth  Lecture,  are  injurious; 
but  it  is  probably  in  consequence  of  their  supplying  an 
excess  of  ferruginous  matter  to  the  sap.  Oxide  of 
iron  in  small  quantities  forms  an  useful  part  of  soils; 
and,  as  is  evident  from  the  details  ia  the  Third  Lec- 
ture, it  is  found  in  the  ashes  of  plants;  and  probably, 
is  hurtful  only  in  its  acid  combinations. 

I  have  just  mentioned  certain  peats,  the  ashes  of 
which  aflbrd  gypsum;  but  it  must  not  be  inferred  from 
this  that  all  peats  agree  with  them.  I  have  examined 
various  peat,  ashes  from  Scotland,  Ireland,  Wales,  and 
the  northern  and  western  parts  of  England,  which 
contained  no  quantity  that  could  be  useful;  and  these 
ashes  abounded  in  siliceous,  aluminous  earths  and 
oxide  of  iron. 

Lord  Charieviile  found  in  some  peat-ashes  from 
Ireland  sulphate  of  potassa;  i.  e.  the  sulphuric  acid 
combined  with  potassa. 

Vitriolic  matter  is  usually  formed  in  peats;  and  if 
the  soil  or  substratum  is  calcareous,  the  ultimate  re- 
sult is  the  production  of  gypsum.  In  general,  when  a 
recent  peat-ash  emits  a  strong  smell  resembling  that 
of  rotten  eggs  when  acted  upon  by  vinegar,  it  will  fur- 
nish gypsum. 

Phosphate  of  lime  is  a  combination  of  phosphoric 
acid  and  lime,  one  proportion  of  each.  It  is  a  com- 
pound insoluble  in  pure  water,  but  soluble  in  water 


[  300  ] 

containing  any  acid  matter.  It  forms  the  greatest 
part  of  calcined  bones.  It  exists  in  most  excremen- 
titious  substances,  and  is  found  both  in  the  straw  and 
grain  of  wheat,  barley^  oats  and  rye,  and  hkewise  in 
beans,  peas  and  tares.  It  exists  in  some  places  in 
these  islands  native;  but  only  in  very  small  quantities. 
Phosphate  of  lime  is  generally  conveyed  to  the  land  in 
the  composition  of  other  manure;  and  it  is  probably 
necessary  to  corn  crops  and  other  white  crops. 

Bone  ashes  ground  to  powder  will  probably  be 
found  useful  on  arable  lands  containing  much  vegeta- 
ble matter;  and  may  perhaps  enable  soft  peats  to  pro- 
duce wheat;  but  the  powdered  bone  in  an  uncalcined 
state  is  much  to  be  preferred  in  all  cases  when  it  can 
be  procured. 

The  Saline  compounds  of  magnesia  will  require 
very  little  discussion  as  to  their  uses  as  manures.^ 
The  most  important  relations  of  this  subject  to  agri- 
culture have  been  considered  in  the  former  part  of 
this  Lecture,  when  the  application  of  the  magnesian 
limestone  was  examined.  In  combination  with  sul- 
phuric acid  magnesia  forms  a  soluble  salt.  This  sub- 
stance, it  is  stated  by  some  enquirers,  has  beeen  found 
of  use  as  a  manure;  but.it  is  not  found  in  nature  in  suf- 
ficient abundance,  nor  is  it  capable  of  being  made  ar- 
tificially sufficiently  cheap  to  be  of  useful  application  in 
the  common  course  of  husbandry. 

Wood  ashes  consist  principally  of  the  vegetable 
alkali  united  to  carbonic  acid;  and  as  this  alkali  is 
found  in  almost  all  plants,  it  is  not  difficult  to  con- 
ceive that  it  may  form  an  essential  part  of  their  or- 


C  301  J 

gans.  The  general  tendency  of  the  alkalies  is  to  give 
solubility  to  vegetable  matters  ;  and  in  this  way  they 
may  render  carbonaceous  and  other  substances  capa- 
ble of  being  taken  up  by  the  tubes  in  the  radicle 
fibres  of  plants.  The  vegetable  alkali  likewise  has  a 
strong  attraction  for  water,  and  even  in  small  quanti- 
ties may  tend  to  give  a  due  degree  of  moisture  to  the 
soil,  or  to  other  manures  ;  though  this  operation  from 
the  small  quantities  used,  or  existing  in  the  soil,  can 
be  only  of  a  secondary  kind. 

The  mineral  alkali  or  soda^  is  found  in  the  ashes 
of  sea- weed,  and  may  be  procured  by  certain  chemical 
agencies  from  common  salt.  Common  salt  consists  of 
the  metal  named  sodium,  combined  with  chlorine; 
and  pure  soda  consists  of  the  same  metal  united  to 
oxygene.  When  water  is  present  which  can  afford 
oxygene  to  the  sodium,  soda  may  be  obtained  in  se- 
veral modes  from  salt. 

The  same  reasoning  will  apply  to  the  operation 
of  the  pure  mineral  alkaH,  or  the  carbonated  alkali,  as 
to  that  of  the  vegetable  alkali ;  and  when  common  salt 
acts  as  a  manure,  it  is  probably  by  entering  into  the 
composition  of  the  plant  in  the  same  manner  as  gyp- 
sum,  phosphate  of  lime,  and  the  alkalies.  Sir  John 
Pringle  has  stated,  that  salt  in  small  quantities  assists 
the  decomposition  of  animal  and  vegetable  matter. 
This  circumstance  may  render  it  useful  in  certain 
soils.  Common  salt  likewise  is  offensive  to  insects.— 
That  in  small  quantities  it  is  sometimes  a  useful  man- 
ure, I  believe  it  fully  proved  ;  and  it  is  probable  that 
its  efficacy  depends  upon  many  combined  causes. 


L  ^C>2  J 

Some  persons  have  argued  against  the  employ- 
ment of  salt ;  because  when  used  in  large  quantities, 
it  either  does  no  good,  or  renders  the  ground  sterile ; 
but  this  is  a  very  unfair  mode  of  reasoning.  That  salt 
in  large  quantities  rendered  land  barren,  was  known 
long  before  any  records  of  agricultural  science  exist- 
ed. We  read  in  the  Scriptures,  that  Abimelech  took 
the  city  of  Shechem,  "and  beat  down  the  city,  and 
sowed  it  with  salt ;"  that  the  soil  might  be  for  ever  un- 
fruitful. Virgil  reprobates  a  salt  soil ;  and  Pliny, 
though  he  recommends  giving  salt  to  cattle,  yet  af- 
firms, that  when  strewed  over  land  it  renders  it  bar- 
ren. But  these  are  not  arguments  against  a  proper 
application  of  it.  Refuse  salt  in  Cornwall,  which,  how- 
ever, likewise  contains  some  of  the  oil  and  exuviae  of 
fish,  has  long  been  known  as  an  admirable  manure. 
And  the  Cheshire  farmers  contend  for  the  benefit  of 
the  peculiar  produce  of  their  country. 

It  is  not  unlikely  that  the  same  causes  influence 
the  effects  of  salt,  as  those  which  act  in  modifying  the 
operation  of  gvpsum.  Most  lands  in  this  Island,  par- 
ticularly those  near  the  sea,  probably  contain  a  suffi- 
cient  quantity  of  salt  for  all  the  purposes  of  vegetation  ; 
and  in  such  cases  the  supply  of  it  to  the  soil  will  not 
only  be  useless,  but  may  be  injurious.  In  great 
storms  the  spray  of  the  sea  has  been  carried  more 
than  50  miles  from  the  shore  ;  so  that  from  this 
source  salt  must  be  often  supplied  to  the  soil.  I  have 
found  salt  in  all  the  sandstone  rocks  that  I  have  ex^ 
amined,  and  it  must  exist  in  the  soil  derived  from 
these  rocks.  It  is  a  constituent  likewise  of  almost 
every  kind  of  animal  and  vegetable  manure. 


[  303  ] 

Besides  these  compounds  of  the  alkalme  earths 
and  alkalies,  many  others  have  been  recommended 
for  the  purposes  of  increasing  vegetation  ;  such  are 
nitre,  or  the  nitrous  acid  combined  with  potassa.  Sir 
Kenelm  Digby  states,  that  he  made  barley  grow  very 
luxuriantly  by  watering  it  with  a  very  weak  solution 
of  nitre ;  but  he  is  too  speculative  a  writer  to  awaken 
confidence  in  his  results.  This  substance  consists  of 
one  proportion  of  azote,  six  of  oxygene,  and  one  of 
potassium  ;  and  it  is  not  unlikely  that  it  may  furnish 
azote  to  form  albumen  or  gluten  in  those  plants  that 
contain  them  ;  but  the  nitrous  salts  are  too  valuable 
for  other  purposes  to  be  used  as  manures. 

Dr.  Home  states,  that  sulphate  of  potassa,  which 
as  I  just  now  mentioned,  is  found  in  the  ashes  of  some 
peats,  is  a  useful  manure.  But  Mr.  Naismith*  ques- 
tions his  results ;  and  quotes  experiments  hostile 
to  his  opinion,  and,  as  he  conceives,  unfavourable  to 
the  efficacy  of  any  species  of  saline  manure. 

Much  of  the  discordance  cf  the  evidence  relating 
to  the  efficacy  of  saline  substances  depends  upon  the 
circumstance  of  their  having  been  used  in  different 
proportions,  and  in  general  in  quantities  much  too 
large. 

I  made  a  number  of  experiments  in  May  and 
June,  1807,  on  the  effects  of  different  saline  substan- 
stances  on  barley  and  on  grass  growing  in  the  same 
garden,  the  soil  of  which  was  a  light  sand,  of  which 
100  parts   were  composed  of  60  parts    of  silice- 


•  Element*  of  Agiicultupe,  p.  7», 


[  S04  ] 

ous  sand,  and  24  parts  finely  divided  matter,  consist- 
ing of  7  parts  carbonate  of  lime,  12  parts  alumina 
and  silica,  less  than  one  part  saline  matter,  principally 
common  salt,  with  a  trace  of  gypsum  and  sulphate  of 
magnesia:  the  remaining  16  parts  were  vegetable 
matter. 

The  solutions  of  the  saline  substances  were  used 
twice  a  week,  in  the  quantity  of  two  ounces,  on  spots 
of  grass  and  corn,  sufficiently  remote  from  each  other 
to  prevent  any  interference  of  results.  The  substan- 
ces tried  were  super-carbonate^  sulphate^  acetate,  ni- 
trate,  and  muriate  of  pot  ass  a  ;  sulphate  of  soda,  sul- 
phate, nitrate,  muriate,  and  carbonate  of  ammonia,  I 
found  that  in  all  cases  when  the  quantity  of  the  salt 
equalled  ^^^  part  of  the  weight  of  the  water,  the  effects 
were  injurious  ;  but  least  so  in  the  instances  of  the 
carbonate,  sulphate,  and  muriate  of  ammonia.  When 
the  quantities  of  the  salts  were  300  part  of  the  solution 
the  effects  were  different.  The  plants  watered  with 
the  solutions  of  the  sulphates  grew  just  in  the  same 
manner  as  similar  plants  watered  with  rain  water. 
Those  acted  on  by  the  solution  of  nitre,  acetate,  and 
super-carbonate  of  potassa,  and  muriate  of  ammonia 
grew  rather  better.  Those  treated  with  the  solution 
of  carbonate  of  ammonia  grew  most  luxuriantly  of  all. 
This  last  result  is  what  might  be  expected,  for  car- 
bonate of  ammonia  consists  of  carbon,  hydrogene, 
azote,  and  oxygene.  There  was,  however,  another 
result  which  I  had  not  anticipated  ;  the  plants  water- 
ed with  solution  of  nitrate  of  ammonia  did  not  grow 
better  than  those  watered  with  rain  water.    The  solu- 


[         305         ] 

tion  reddened  litmus  paper;  and  probably  the  free  acid 
exerted  a  prejudicial  effect,  and  interfered  with  the  re- 
sult. 

Soot  doubtless  owes  a  part  of  its  efficacy  to  the 
ammoniacal  salts  it  contains  The  liquor  produced  by 
the  distillation  of  coal  contains  carbonate  and  acetate 
of  ammonia,  and  is  said  to  be  a  very  good  manure. 

In  1 808,  I  found  the  growth  of  wheat  in  a  field  at 
Roehampton  assisted  by  a  very  weak  solution  of  ace- 
tate of  ammonia. 

Soapers'  waste  has  been  recommended  as  a  man- 
ure, and  it  has  been  supposed  that  its  efficacy  depend- 
ed upon  the  different  saline  matters  it  contains;  but 
their  quantity  is  very  minute  indeed,  and  its  principal 
ingredients  are  mild  lime  and  quicklime.  In  the  soap- 
ers'  waste  from  the  best  manufactories,  there  is  scarce- 
ly a  trace  of  alkali.  Lime  moistened  with  sea  water 
affords  more  of  this  substance,  and  is  said  to  have 
been  used  in  some  cases  with  more  benefit  than  com- 
mon lime. 

It  is  unnecessay  to  discuss  to  any  greater  extent 
the  effects  of  saline  substances  on  vegetation;  except 
the  ammoniacal  compounds,  or  the  compounds  con- 
taining nitric,  acetic,  and  carbonic  acid;  none  of  them 
can  afford  by  their  decomposition  any  of  the  common 
principles  of  vegetation,  carbon,  hydrogene,  and  oxy. 
gene. 

The  alkaline  sulphates  and  the  earthy  muriates 
are  so  seldom  found  in  plants,  or  are  found  in  such 
minute  quantities,  that  it  can  never  be  an  object 
to  apply  them  to  the  soil.     It  was  stated  in  the  begin* 

R  2 


I  306         2 

liing  of  this  Lecture,  that  the  earthy  and  alkaline  sub- 
stances  seem  never  to  be  formed  in  vegetation;  and 
there  is  every  reason  likewise  to  believe,  that  they  are 
never  decomposed;  for  after  being  absorbed  they  are 
found  in  their  ashes. 

The  metallic  bases  of  them  cannot  exist  in  con- 
tact with  aqueous  fluids;  and  these  metallic  bases, 
like  other  metals,  have  not  as  yet  been  resolved  into 
any  other  forms  of  matter  by  artificial  processes;  they 
combine  readily  with  other  elements;  but  they  remain 
iindestructible,  and  can  be  traced  undiminished  in 
quantity,  through  their  diversified  combinations. 


;o7 


LECTURE  ViiL 

On  the  Improvement  of  Lands  by  Burning;  chemical 
Principles  of  this  Operation.  On  Irrigation  and  its 
effects.  On  Fallowing;  its  Disadvantages  and 
Uses.  On  the  convertible  Husbandry  founded  on 
regular  Rotations  of  different  Crops,  On  Pasture; 
Views  connected  with  its  Application,  On  various 
Agricultural  Objects  connected  with  Chemistry, 
Conclusion, 

The  improvement  of  sterile  lands  by  burning 
was  known  to  the  Romans.  It  is  mentioned  by  Vir- 
gil in  the  first  book  of  the  Georgics:  ''  Saepe  etiam 
steriles  incendere  profuit  agros."  It  is  a  practice  still 
much  in  use  in  many  parts  of  these  Islands;  the  theory 
of  its  operation  has  occasioned  much  discussion;  both 
amongst  scientific  men  and  farmers.  It  rests  entirely 
upon  chemical  doctrines;  and  I  trust  I  shall  be  able  to 
offer  you  satisfactory  elucidations  on  the  subject. 

The  basis  of  all  common  soils,  as  I  stated  in  the 
Fourth  Lecture,  are  mixtures  of  the  primitive  earths 
and  oxide  of  iron;  and  these  earths  have  a  certain  de- 
gree of  attraction  for  each  other.  To  regard  this  at- 
traction  in  its  proper  point  of  view,  it  is  only  necessary 
to  consider  the  composition  of  any  common  siliceous 


[  308  ] 

Stone.  Feldspar,  for  instance,  contains  siliceous,  al- 
uminous, calcareous  earths,  fixed  alkali,  and  oxide  of 
iron,  which  exist  in  one  compound,  in  consequence  of 
their  chemical  attractions  for  each  other.  Let  this 
stone  be  ground  into  impalpable  powder,  it  then  be- 
comes a  substance  like  clay:  if  the  powder  be  heated 
very  strongly  it  fuses,  and  on  cooling  forms  a  coher- 
ent mass  similar  to  the  original  stone;  the  parts  separ- 
ated by  mechanical  division  adhere  again  in  conse- 
quence of  chemical  attraction.  If  the  powder  is  heat- 
ed less  strongly  the  particles  only  superficially  com* 
bine  with  each  other,  and  form  a  gritty  mass,  which, 
when  broken  in  to  pieces,  has  the  characters  of  sand. 

If  the  power  of  the  powdered  feldspar  to  absorb 
water  from  the  atmosphere  before,  and  after  the  ap- 
plication of  the  heat,  be  compared,  it  is  found  much 
less  in  the  last  case. 

The  same  effect  takes  place  when  the  powder  of 
other  siliceous  or  aluminous  stones  is  made  the  sub- 
ject of  experiment. 

I  found  that  two  equal  portions  of  basalt  ground 
into  impalpable  powder,  of  which  one  had  been  strong- 
ly ignited,  and  the  other  exposed  only  to  a  temperature 
equal  to  that  of  boiling  water,  gained  very  different 
weights  in  the  same  time  when  exposed  to  air.  In 
four  hours  the  orie  had  gained  only  two  grains,  whilst 
the  other  had  gained  seven  grains. 

When  clay  or  tenacious  soils  are  burnt,  the  effect 
is  of  the  same  kind;  they  are  brought  nearer  to  a  state 
analogous  to  that  of  sands. 


[  309  3 

In  the  manufacture  of  bricks  the  general  principle 
'is  well  illustrated  ;  if  a  piece  of  dry  brick  earth  be  ap- 
plied to  the  tongue  it  will  adhere  to  it  very  strongly, 
in  consequence  of  its  power  to  absorb  water ;  but  af- 
ter  it  has  been  burnt  there  will  be  scarcely  a  sensible 
adhesion. 

The  process  of  burning  renders  the  soil  less  com- 
pact, less  tenacious  and  retentive  of  moisture ;  and 
when  properly  applied,  may  convert  a  matter  that  was 
stiff,  damp,  and  in  consequence  cold,  into  one  pow- 
dery, dry,  and  warm  j  and  much  more  proper  as  a 
bed  for  vegetable  life. 

The  great  objection  made  by  speculative  chemists 
to  paring  and  burning,  is,  that  it  destroys  vegetable 
and  animal  matter,  or  the  manure  in' the  soil ;  but  in 
cases  in  which  the  texture  of  its  earthy  ingredients  is 
permanently  improved,  th^re  is  more  than  a  compen- 
sation for  this  temporary  disadvantage.  And  in  some 
soils  where  there  is  an  excess  of  inert  vegetable  mat- 
ter, the  destruction  of  it  must  be  beneficial ;  and  the 
carbonaceous  matter  remaining  in  the  ashes  may  be 
more  useful  to  the  crop  than  the  vegetable  fibre,  from 
which  it  was  produced. 

I  have  examined  by  a  chemical  analysis  three 
specimens  of  ashes  from  different  lands  that  had  un- 
dergone paring  and  burning.  The  first  was  a  quanti- 
ty sent  to  the  Board  by  Mr.  Boys  of  Bellhanger,  in 
Kent,  whose  treatise  on  paring  and  burning  has  been 
published.  They  were  from  a  chalk  soil,  and  200 
grains  contained 

80  Carbonate  of  lime, 
11  Gypsum. 


C  310  J 

9  Charcoal. 
15  Oxide  of  iron. 
5  Saline  matter. 
Sulphate  of  potash. 
Muriate  of  magnesia,  with  a  minute 
quantity  of  vegetable  alkali. 
The  remainder  alumina  and  silica. 

Mr.  Boys  estimates  that  2660  bushels  are  the 
common  produce  of  an  acre  of  ground,  which,  accor- 
ding to  his  calculation  would  give  172900  lbs.  con- 
taining 

Carbonate  of  lime     69 1 60  lbs. 
Gypsum  .  9509.5 

Oxide  of  iron  12967.5 

Saline  matter  2593.5 

Charcoal  7780.5 

In  this  instance  there  was  undoubtedly  a  very 
considerable  quantity  of  matter  capable  of  being  ac- 
tive as  manure  produced  in  the  operation  of  burning. 
The  charcoal  was  very  finely  divided ;  and  exposed 
on  a  large  surface  on  the  field,  must  have  been  gradu- 
ally converted  into  carbonic  acid.  And  gypsum  and 
oxide  of  iron,  as  I  mentioned  in  the  last  Lecture,  seem 
to  produce  the  very  best  effects  when  applied  to  lands 
containing  an  excess  of  carbonate  of  lime. 

The  second  specimen  was  from  a  soil  near  Cole- 
©rton,  in  Leicestershire,  containing  only  four  per  cent, 
of  carbonate  of  lime,  and  consisting  of  three-fourths 
light  siliceous  sand,  and  about  one-fourth  clay.  This 
had  been  turf  before  burning,  and  100  parts  of  the 
ashes  gave 


L       ^n       j 

6  parts  charcoal. 

3  Muriate  of  soda  and  sulphate  of  potash, 

with  a  trace  of  vegetable  alkali. 
9  Oxide  of  iron. 
And  the  remainder  the  earths. 

In  this  instance,  as  in  the  other,  finely  divided 
charcoal  was  found  ;  the  solubility  of  which  would  be 
increased  by  the  presence  of  the  alkali. 

The  third  instance  was,  that  of  a  stiff  clay,  from 
Mount's  Bay  Cornwall.  This  land  had  been  brought 
into  cultivation  from  a  heath  by  burning  about  ten 
years  before ;  t^ut  having  been  neglected,  furze  was 
springing  up  in  different  parts  of  it,  which  gave  rise 
to  the  second  paring  and  burning.  100  parts  of  the 
ashes  contained 

8  parts  of  charcoal. 

2  of  saline  matter,  principally  common  salt, 
with  a  little  vegetable  alkali. 

7  Oxide  of  iron. 

2  Carbonate  of  lime. 
Remainder  alumina  and  silica. 

Here  the  quantity  of  charcoal  was  greater  than  in 
the  other  instances.  The  salt,  I  suspect,  was  owing 
to  the  vicinity  of  the  sea,  it  being  but  two  miles  offl 
In  this  land  there  was  certainly  an  excess  of  dead  ve- 
getable fibre,  as  well  as  unprofitable  living  vegetable 
matter  ;  and  I  have  since  heard,  that  a  great  improve- 
ment took  place. 

Many  obscure  causes  have  been  referred  to  for 
the  purpose  of  explaining  the  effects  of  paring  and 
burning  ;  and  I  believe  they  may  be  referred  entirely 


C      312      3 

to  the  diminution  of  the  coherence  and  tenacity  of 
clays,  and  to  the  destruction  of  inert,  and  useless  ve- 
getable matter,  and  its  conversion  into  a  manure. 

Dr.  Darwin,  in  his  Phytologia,  has  supposed, 
that  clay  during  torrefaction,  may  absorb  some  nutri- 
tive principles  from  the  atmosphere  that  afterwards 
may  be  supplied  to  plants  ;  but  the  earths  are  pure 
metallic  oxides,  saturated  with  oxygene ;  and  the  ten- 
dency of  burning  is  to  expel  any  other  volatile  princi- 
ples that  they  may  contain  in  combination.  If  the 
oxide  of  iron  in  soils  is  not  saturated  with  oxygene, 
torrefaction  tends  to  produce  its  further  union  with 
this  principle ;  and  hence  in  burning,  the  colour  of 
clays  changes  to  red.  The  oxide  of  iron  containing 
its  full  proportion  of  oxygene  has  less  attraction  for 
acids  than  the  other  oxide,  and  is  consequently  lass 
likely  to  be  dissolved  by  any  fluid  acids  in  the  soil ; 
and  it  appears  in  this  state  to  act  in  the  same  manner 
as  the  earths,  A  very  ingenious  author,  whom  I 
quoted  at  the  end  of  the  last  Lecture,  supposes  that  the 
oxide  of  iron  when  combined  with  carbonic  acid  is 
poisonous  to  plants  ;  and  that  one  use  of  torrefaction 
is  to  expel  the  carbonic  acid  from  it ;  but  the  carbon- 
ate of  iron  is  not  soluble  in  water,  and  is  a  very  inert 
substance  ;  and  I  have  raised  a  luxuriant  crop  of  cres- 
ses in  a  soil  composed  cf  one-fifth  carbonate  of  iron, 
and  four-fifths  carbonate  of  lime.  Carbonate  of  iron 
abounds  in  some  of  the  most  fertile  soils  in  England ^ 
particularly  the  red  hop  soil.  And  there  is  no  theo- 
retical ground  for  supposing,  that  carbonic  acid,  which 
is  an  essential  food  of  plants,  should  in  any  of  its  com- 


C  313  J 

binations  be  poisonous  to  themj  and  it  is  known  that 
lime  and  magnesia  are  both  noxious  to  vegetation, 
unless  combined  with  this  principle. 

All  soils  that  contain  too  much  dead  vegetable 
fibre,  and  which  consequently  lose  from  one  third  to 
one-half  of  their  weight  by  incineration,  and  all  such 
as  contain  their  earthy  constituents  in  an  impalpable 
state  of  division,  i.  e.  the  stiff  clays  and  marles,  are  im- 
proved by  burning;  but  in  coarse  sands,  or  rich  soils 
containing  a  just  mixture  of  the  earths;  and  in  all  ca- 
ses in  which  the  texture  is  already  sufficiently  loose, 
or  the  organizable  matter  sufficiently  soluble,  the  pro- 
cess of  torrefaction  cannot  be  useful. 

All  poor 'Siliceous  sands  must  be  injured  by  it; 
and  here  practice  is  found  to  accord  with  the  theory. 
Mr.  Young,  in  his  Essay  on  Manures,  states,  "  that 
he  found  burning  injure  sand;"  and  the  operation  is 
never  performed  by  good  agriculturists  upon  siliceous  * 
sandy  soils,  after  they  have  oncie  been  brought  into 
cultivation. 

An  intelligent  farmer  in  Mount's  Bay  told  me, 
that  he  had  pared  and  burned  a  small  field  sevei^al 
years  ago,  which  he  had  not  been  able  to  bring  again 
into  good  condition.  I  examined  the  spot,  the  grass  was 
very  poor  and  scanty,  and  the  soil  an  arid  siliceous 
sand. 

Irrigation  or  Watering  land^  is  a  practice,  which 
at  first  viev/,  appears  the  reverse  of  torrefection;  and 
in  general,  in  nature,  the  operation  of  water  is  to  bring 
earthy  substances  into  an  extreme  state  of  division 
But  in  the  artificial  watering  of  meadows,  the  benefi- 

S2 


C       SI*      1 

ciai  effects  depend  upon  many  different  causes,  some 
chemical,  some  mechanical. 

Water  is  absolutely  essential  to  vegetation;  and 
when  land  has  been  covered  by  water  in  the  winter, 
or  in  the  beginning  of  spring,  the  moisture  that  has 
penetrated  deep  into  the  soil,  and  even  the  subsoil^ 
becomes  a  source  of  nourishment  to  the  roots  of  the 
plant  in  the  summer,  and  prevents  those  bad  effects 
that  often  happen  in  lands  in  their  natural  state,  from 
a  long  continuance  of  dry  weather. 

When  the  water  used  in  irrigation  has  flowed 
over  a  calcareous  country,  it  is  generally  found  im- 
pregnated with  carbonate  of  lime;  and  in  this  state  it 
tends,  in  many  instances,  to  ameliorate  the  soil. 

Common  river  water  also  generally  contains  a 
certain  portion  of  organizable  matter,  which  is  much 
greater  afier  rains,  than  at  other  times;  and  which  ex- 
ists in  the  largest  quantity  when  the  stream  rises  in  a 
cultivated  country. 

Even  in  cases  when  the  water  used  for  flooding 
is  pure,  and  free  from  animal  or  vegetable  substances, 
it  acts  by  causing  the  more  equable  diffusion  of  nutri- 
tive matter  existing  in  the  land;  and  in  Very  cold  sea-* 
sons  it  preserves  the  tender  roots  and  leaves  of  the 
grass  from  being  affected  by  frost. 

Water  is  of  greater  specific  gravity  at  42°  Fah- 
renheit, than  at  32'',  the  freezing  point;  and  hence  in 
a  meadow  irrigated  in  winter,  the  water  immediately 
in  contact  with  the  grass  is  rarely  below  40°,  a  degree 
of  temperature  not  at  all  prejudicial  to  the  living  or- 
gans of  plants. 


C         315         3 

'  In  1804-,  in  the  month  of  March,  I  examined 
the  temperature  in  a  water  meadow  near  Hungerford> 
in  Berkshire,  by  a  very  dehcate  thermometer.  The 
temperature  of  the  air  at  seven  in  the  morning  was 
29°.  The  water  was  frozen  above  the  grass.  The 
temperature  of  the  soil  below  the  water  in  which  the 
roots  of  the  grass  were  fixed,  was  43°. 

In  general  those  waters  which  breed  the  best  fish 
are  the  best  fitted  for  watering  meadows;  but  most  of 
the  benefits  of  irrigation  may  be  derived  from  any  kind 
of  water.  It  is,  however,  a  general  principle,  that  wa- 
ters containing  ferruginous  impregnations,  though 
possessed  of  fertilizing  effects,  when  applied  to  a  cal- 
careous soil,  are  injurious  on  soils  that  do  not  effer- 
vesce with  acids;  and  that  calcareous  waters  which  are 
known  by  the  earthy  deposit  they  afford  when  boiled, 
are  of  most  use  on  siliceous  soils,  or  other  soils  con- 
taining no  remarkable  quantity  of  carbonate  of  lime* 

The  most  important  processes  for  improving 
land,  are  those  which  have  been  already  discussed, 
and  that  are  founded  upon  the  circumstance  of  remo- 
ving certain  constituents  from  the  soil,  or  adding 
others  or  changing  their  nature;  but  there  is  an  opera- 
tion of  very  ancient  practice  still  much  employed,  in 
which  the  soil  is  exposed  to  the  air  and  submitted  to 
processes  which  are  purely  mechanical,  namely, 
fallozving. 

The  benefits  arising  from  fallows  have  been  much 
over-rated.  A  summer  fallow,  or  a  clean  fallow, 
may  be  sometimes  necessary  in  lands  overgrown  with 
weeds,  particularly  if  they  are  sands  which  cannot  be 


L         316  ]  , 

pared  and  burnt  with  advantage;  but  it  is  certainly  un- 
profitable as  part  of  a  general  system  in  husbandry. 

It  has  been  supposed  by  some  writers,  that  cer- 
tain  principles  necessary  to  fertility  are  derived  from 
the  atmosphere,  which  are  exhausted  by  a  succession 
of  crops,  and  that  these  are  again  supplied  during  the 
repose  of  the  land,  and  the  exposure  of  the  pulverised 
soil  to  the  influence  of  the  air;  but  this  in  truth  is  not 
the  case.  The  earths  commonly  found  in  soils  can- 
not be  combined  with  more  oxygene;  none  of  them 
unite  to  azote;  and  such  of  them  as  are  capable  of  ati- 
tracting  carbonic  acid,  are  always  saturated  with  it  in 
those  soils  on  which  the  practice  of  fallowing  is  adopt- 
ed. The  vague  ancient  opinion  of  the  use  of  nitre, 
and  of  nitrous  salts  in  vegetation,  seems  to  have  been 
one  of  the  principal  speculative  reasons  for  the  de- 
fence of  summer  fallows.  Nitrous  salts  are  produced 
during  the  exposure  of  soils  containing  vegetable  and 
animal  remains,  and  in  greatest  abundance  in  hot  wea- 
ther; but  it  is  probably  by  the  combination  of  azote 
from  these  remains  with  oxygene  in  the  atmosphere 
that  the  acid  is  formed;  and  at  the  expence  of  an  ele- 
ment, which  otherwise  would  have  formed  ammonia; 
the  compounds  of  which,  as  is  evident  from  what  was 
stated  in  the  last  Lecture,  are  much  more  efficacious 
than  the  nitrous  compounds  in  assisting  vegetation. 

When  weeds  are  buried  in  the  soil,  by  their  gra- 
dual decomposition  they  furnish  a  certain  quantity  of 
soluble  matter;  but  it  may  be  doubted  whether  there 
is  as  much  useful  manure  in  the  land  at  the  end  of  a 
clean  fallow,  as  at  the  time  the  vegetables  clothing  the 


C         317         3 

surface  were  first  ploughed  in.  Carbonic  acid  gas 
is  formed  during  the  whole  time  by  the  action  of  the 
vegetable  matter  upon  the  oxygene  of  the  air,  and  the 
greater  part  of  it  is  lost  to  the  soil  in  which  it  Was 
formed,  and  dissipated  in  the  atmosphere. 

The  action  of  the  sun  upon  the  surface  of  the 
soil  tends  to  disengage  the  gaseous  and  the  volatile 
fluid  matters  that  it  contains ;  and  heat  increases  the 
rapidity  of  fermentation  :  and  in  the  summer  fallow, 
nourishment  is  rapidly  produced,  at  a  time  when  no 
vegetables  are  present  capable  of  absorbing  it. 

Land  when  it  is  not  employed  in  preparing  food 
for  animals,  should  be  applied  to  the  purpose  of  the 
preparation  of  manure  for  plants  ;  and  this  is  effected 
by  means  of  green  crops,  in  consequence  of  the  ab- 
sorption of  carbonaceous  matter  in  the  carbonic  acid 
of  the  atmosphere.  In  a  summer's  fallow  a  period  is 
always  lost  in  which  vegetables  may  be  raised,  either 
as  food  for  animals,  or  as  nourishment  for  the  next 
crop  ;  and  the  texture  of  the  soil  is  not  so  much  im- 
proved by  its  exposure  as  in  winter,  when  the  expan- 
sive powers  of  ice,  the  gradual  dissolution  of  snows, 
and  the  alternations  from  w^et  to  dry,  tend  to  pulverize 
it,  and  to  mix  its  different  parts  together. 

In  the  drill  husbandry  the  land  is  preserved 
clean  by  the  extirpation  of  the  weeds  by  hand,  and  by 
raising  the  crops  in  rows,  which  renders  the  destruc- 
tion of  the  weeds  much  more  easy.  Manure  is  sup- 
plied either  by  the  green  crops  themselves,  or  from 
the  dung  of  the  cattle  fed  upon  them  ;  and  the  plants 
having  large  systems  of  leaves,  are  made  to  alternate 
with  those  bearing  grain. 


E         318         ] 

It  is  a  great  advantage  in  the  convertible  system 
of  cultivation,  that  the  whole  of  the  manure  is  em- 
ployed ;  and  that  those  parts  of  it  which  are  not  fitted 
for  one  crop,  remain  as  nourishment  for  another. 
Thus,  in  Mr.  Coke's  course  of  crops,  the  turnip  is  the 
•first  in  the  order  of  succession  ;  and  this  crop  is  man- 
ured with  recent  dung,  which  immediately  affords  suf- 
ficient soluble  matter  for  its  nourishment ;  and  the  heat 
produced  in  fermentation  assists  the  germination  of 
the  seed  and  the  growth  of  the  plant.  After  turnips, 
barley  with  grass  seeds  is  sown ;  and  the  land  having 
been  little  exhausted  by  the  turnip  crop^  affords  the 
soluble  parts  of  the  decomposing  manure  to  the  grain. 
The  grasses,  rye  grass,  an*-^  clover  remain,  which  de- 
rive a  small  part  only  of  their  organised  matter  from 
the  soil,  and  probably  consume  the  gypsum  in  the 
manure  which  would  be  useless  to  other  crops  :  these 
plants  likewise  by  their  large  systems  of  leaves^  absorb 
a  considerable  quantity  of  nourishment  from  the  atmos- 
phere y  and  when  ploughed  in  at  the  end  of  two  years, 
the  decay  of  their  roots  and  leaves  affords  manure  for 
the  wheat  crop ;  and  at  this  period  of  the  course,  the 
woody  fibre  of  the  farm-yard  manure  which  contains 
the  phosphate  of  lime  and  the  other  difficultly  soluble 
parts,  is  broken  down  :  and  as  soon  as  the  most  ex- 
hausting crop  is  taken,  recent  manure  is  again  ap- 
plied. 

Mr.  Gregg,  whose  very  enlightened  system  of 
cultivation  has  been  published  by  the  Board  of  Agri- 
culture, and  who  has. the  merit  of  first  adopting  a  plan 
similar  to  Mr.  Coke's  upon  strong  clays,  suffers  the 


C         S19         ] 

ground  after  barley  to  remain  at  rest  for  two  years  in 
grass  ;  sows  peas  and  beans  on  the  lays  ;  ploughs  in 
the  pea  or  bean  stubble  for  wheat ;  and  in  some  in- 
stances, follows  his  wheat  crops  by  a  course  of  winter 
tares  and  winter  barley,  which  is  eat  off  in  the  spring, 
before  the  land  is  sowed  for  turnips. 

Peas  and  beans,  in  all  instances,  seem  well  adapt- 
ed  to  prepare  the  ground  for  wheat ;  and  in  some 
rich  lands,  as  in  the  alluvial  soil  of  the  Parret,  men- 
tioned in  the  Fourth  Lecture,  and  at  the  foot  of  the 
South  Downs  in  Sussex,  they  are  raised  in  alternate 
crops  for  years  together.  Peas  and  beans  contain,  as 
appears  from  the  analyses  in  the  Third  Lecture,  a 
small  quantity  of  a  matter  analogous  to  albumen  ;  but 
it  seems  that  the  azote  which  forms  a  constituent  part 
of  this  matter,  is  derived  from  the  atmosphere.  The 
dry  bean  leaf,  when  burnt,  yields  a  smell  approaching 
to  that  of  decomposing  animal  matter ;  and  in  its  de- 
cay  in  the  soil,  may  furnish  principles  capable  of  be- 
coming a  part  of  the  gluten  in  wheat. 

Though  the  general  composition  of  plants  is  very 
analogous,  yet  the  specific  difference  in  the  products 
of  many  of  them,  and  the  facts  stated  in  the  last  Lec- 
ture, prove  that  they  must  derive  different  materials 
from  the  soil ;  and  though  the  vegetables  having  the 
smallest  systems  of  leaves  will  proportionably  most 
exhaust  the  soil  of  common  nutritive  matter,  yet  par- 
ticular vegetables  when  their  produce  is  carried  off, 
will  require  peculiar  principles  to  be  supplied  to  the 
land  in  which  they  grow.  Strawberries  and  potatoes 
at  first  prod\ice  luvitrrantly  in  virgin  mould  recently 


C  320  J 

turned  up  from  pasture  ;  but  in  a  few  years  they  de* 
generate,  and  require  a  fresh  soil ;  and  the  organiza- 
tion of  these  plants  is  such,  as  to  be  constantly  pro- 
ducing the  migration  of  their  layers  :  thus  the  straw- 
berry by  its  long  shoots  is  constantly  endeavouring  to 
occupy  a  new  soil  ;  and  the  fibrous  radicles  of  the 
potatoe  produce  bulbs  at  a  considerable  distance  from 
the  parent  plant.  Lands  in  a  course  of  years  often 
cease  to  afford  good  cultivated  grasses  ;  they  become 
(as  it  is  popularly  said)  tired  of  them  ;  and  one  of  the 
probable  reasons  for  this  was  stated  in  the  last  Lec- 
ture. 

The  most  remarkable  instances  of  the  powers  of 
'  vegetables  to  exhaust  the  soil  of  certain  principles  ne- 
cessary to  their  growth  is  found  in  certain  funguses. 
Mushrooms  are  said  never  to  rise  in  two  successive 
seasons  on  the  same  spot ;  and  the  production  of  the 
phaenomena  called  fairy  rings  has  been  ascribed  by 
Dr  Wollaston  to  the  power  of  the  peculiar  fungus 
which  forms  it  to  exhaust  the  soil  of  the  nutriment 
necessary  for  the  growth  of  the  species.  The  conse- 
quence is,  that  the  ring  annually  extends  ;  for  no 
seeds  will  grow  where  their  parents  grew  before  them ; 
and  the  interior  part  of  the  circle  has  been  exhausted 
by  preceding  crops  ;  but  where  the  fungus  has  died, 
nourishn\ent  is  supplied  for  grass,  which  usually  rises 
within  the  circle,  coarse,  and  of  a  dark  green  colour. 

When  cattle  are  fed  upon  land  not  benefitted  by 
their  manure,  the  effect  is  always  an  exhaustion  of  the 
soil  ;  this  is  particularly  the  case  where  carrying 
horses  are  kept  on  estates  5  they  consume  the  pasture 


C  321  3 

during  the  night,  and  drop  the  greatest  part  of  their 
manure  during  their  labour  in  the  day-time. 

The  exportation  of  grain  from  a  country,  unless 
some  articles  capable  of  becoming  manure  are  intro- 
duced in  compensation,  must  ultimately  tend  to  ex- 
haust the  soil.  Some  of  the  spots  now  desart  sands  in 
northern  Africa,  and  Asia  Minor,  were  anciently  fer- 
tile. Sicily  was  the  granary  of  Italy  :  and  the  quan- 
tity of  corn  carried  off  from  it  by  the  Romans,  is  pro- 
bably a  chief  cause  of  its  present  sterility.  In  this  Is- 
land, our  commercial  system  at  present  has  the  effect 
of  affording  substances  which  in  their  use  and  decom- 
position must  enrich  the  land.  Corn,  sugar,  tallow, 
oil,  skins,  furs,  wine,  silk,  cotton,  &c.  are  imported, 
and  fish  are  supplied  from  the  sea.  Amongst  our 
numerous  exports  woollen,  and  linen,  and  leather 
goods,  are  almost  the  only  substances  which  contain 
any  nutritive  materials  derived  from  the  soil. 

In  all  courses  of  crops  it  is  necessary  that  every 
part  of  the  soil  should  be  made  as  useful  as  possible 
to  the  different  plants  ;  but  the  depth  of  the  furrow 
in  ploughing  must  depend  upon  the  nature  of  the  soil, 
and  ot  the  subsoil.  In  rich  clayey  soils  the  furrow 
can  scarcely  be  too  deep ;  and  in  sands,  unless  the 
subsoil  contains  some  principles  noxious  to  vegetables, 
the  same  practice  should  be  adopted.  When  the  roots 
are  deep  they  are  less  liable  to  be  injured,  either  by 
excess  of  rain,  or  drought ;  the  layers  shoot  forth 
their  radicles  into  every  part  of  the  soil  j  and  the 
space  from  which  the  nourishment  is  derived  is  more 

T  2 


I         322         ] 

considerable,  than  when  the  ssed  is  superficially  inser- 
ted in  the  soil. 

There  has  been  much  difference  of  opinion  with 
respect  to  permanent  pasture ;  but  the  advantages  or 
disadvantages  can  only  be  reasoned  upon  according  to 
the  circumstances  of  situation  and  climate.  Under 
the  circumstances  of  irrigation,  lands  are  extremely 
productive  with  comparatively  little  labour;  and  in 
climates  where  great  quantities  of  rain  falls,  the  natur- 
al  irrigation  produces  the  same  effects  as  artificial. 
When  hay  is  in  great  demand,  as  sometimes  happens 
in  the  neighbourhood  of  the  metropolis,  where  man- 
ure can  be  easily  procured,  the  application  of  it  to  pas- 
ture is  repaid  for  by  the  increase  of  crop  ;  but  top- 
dressing  grass  land  with  animal  or  vegetable  manure, 
cannot  be  recommended  as  a  general  system.  •  Dr. 
Coventry  very  justly  observes,  that  there  is  a  greater 
waste  of  the  manure  in  this  case,  than  when  it  is 
ploughed  into  the  soil  for  seed  crops.  The  loss  by 
exposure  to  the  air,  and  the  sunshine,  offer  reasons  in 
addition  to  those  that  have  been  already  quoted  in  the 
Sixth  Lecture,  for  the  application  of  manure  even  in 
this  case,  in  a  state  of  incipient,  and  not  completed 
fermentation. 

Very  little  attention  has  been  paid  to  the  nature 
of  the  grasses  .best  adapted  for  permanent  pasture. 
The  chief  circumstance  which  gives  value  to  a  grass, 
is  the  quantity  of  nutritive  matter  that  the  whole  crop 
will  afford  ;  but  the  time  and  duration  of  its  produce 
are  likewise  points  of  great  importance  ;  and  a  grass 
that  supplies  green  nutriment  throughout  the  whole  of 


[  323  ] 

the  year,  may  be  more  valuable  than  a  grass  which 
yields  its  produce  only  in  summer,  though  the  whole 
quantity  of  food  supplied  by  it  should  be  much  less. 

The  grasses  that  propagate  themselves  by  layers, 
the  different  species  of  Agrostis,  supply  pasture 
throughout  the  year ;  and,  as  it  has  been  mentioned 
on  a  former  occasion,  the  concrete  sap  stored  up  in 
their  joints,  renders  them  a  good  food  even  in  winter. 
I  saw  four  square  yards  of  fiorin  grass  cut  in  the  end 
of  January,  this  year,  in  a  meadow  exclusively  appro- 
priated  to  cultivadon  of  fiorin,  by  the  Countess  of 
Hardwicke,  the  soil  of  which  is  a  damp  stiff  clay. 
They  afforded  28  pounds  of  fodder  ;  of  which  1000 
parts  afforded,  64  parts  of  nutritive  matter,  consisting 
nearly  of  one-sixth  of  sugar,  and  five-sixths  of  mucil- 
age, with  a  little  extractive  matter,  In  another  expe- 
riment, four  square  yards  gave  27  pounds  of  grass. 
The  quality  of  this  grass  is  inferior  to  that  of  the  fio- 
rin referred  to  in  the  Table,  in  the  latter  part  of  the 
Third  Lecture,  which  was  cultivated  by  Sir  Joseph 
Banks  in  Middlesex,  in  a  much  richer  soil,  and  cut  in 
December. 

The  fiorin  grass,  to  be  in  perfection,  requires  a 
moist  climate  or  a  wet  soil ;  and  it  grows  luxuriantly 
in  cold  clays  unfitted  for  other  grasses.  In  light  sands 
and  in  dry  situations  its  produce  is  much  inferior  as 
to  quantity  and  quality. 

The  common  grasses,  properly  so  called,  that 
afford  most  nutritive  matter  in  early  spring,  are  the 
vernal  meadow  grass,  and  meadow  foxtail  grass  ;  but 
their  produce  at  the  time  of  flowering  and  ripening 


[  324         ] 

the  seed,  are  inferior  to  that  of  a  great  number  of 
other  grasses  j  their  latter  math  is,  however,  abun- 
dant 

Tall  fescue  grass  stands  highest,  according  to 
the  experiments  of  the  Duke  of  Bedford,  of  any  grass, 
properly  so  called,  as  to  the  quantity  of  nutritive  mat- 
ter afforded  by  the  whole  crop  when  cut  at  the  time  of 
flowering  ;  and  meadow  cat's-tail  grass  affords  most 
food  when  cut  at  the  time  the  seed  is  ripe  ;  the  high- 
est latter  math  produce  of  the  grasses  examined  in  the 
Duke  of  Bedford's  experiments  is  from  the  sea  mea- 
dow grass. 

Nature  has  provided  in  all  permanent  pastures  a 
mixture  of  various  grasses,  the  produce  of  which  dif- 
fers at  different  seasons.  Where  pastures  are  to  be 
made  artificially  such  a  mixture  ought  to  be  imitated  ; 
and,  perhaps,  pastures  superior  to  the  natural  ones 
may  be  made  by  selecting  due  proportions  of  those 
species  of  grasses  fitted  for  the  soil,  which  afford  res- 
pectively the  greatest  quantities  of  spring,  summer, 
latter  math,  and  winter  produce ;  a  reference  to  the 
details  in  the  Appendix  will  shew^  that  such  a  plan  of 
cultivation  is  very  practicable. 

In  all  lands,  whether  arable  or  pasture,  weeds  of 
ever  description  should  be  rooted  out  before  the  seed 
is  ripe ;  and  if  they  are  suffered  to  remain  in  hedge 
rows,  they  should  be  cut  when  in  flower,  or  before, 
and  made  into  heaps  for  manure  j  in  this  case  they 
will  furnish  more  nutritive  matter  in  their  decomposi- 
tion j  and  their  increase  by  the  dispersion  of  seeds  will 
be  prevented.     The  farmer,  who  suffers  weeds  to  re- 


L  325  3 

main  till  their  ripe  seeds  are  shed,  and  scattered  by 
the  winds,  is  not  only  hostile  to  his  own  interests,  but 
is  likewise  an  enemy  to  the  public:  a  few  thistles  will 
stock  a  whole  farm;  and  by  the  light  down  which  is 
attached  to  their  seeds,  they  may  be  destributed  over 
a  whole  country.  Nature  has  provided  such  ample 
resources  for  the  continuance  of  even  the  meanest  ve- 
getable tribes,  that  it  is  very  difficult  to  ensure  the  de- 
struction of  such  as  are  hostile  to  the  agriculturist, 
even  with  every  precaution.  Seeds  excluded  from 
the  air,  will  remain  for  years  inactive  in  the  soil,*  and 
yet  germinate  under  favourable  circumstances;  and  the 
different  plants,  the  seeds  of  which,  like  those  of  the 
thistle  and  dandelion,  are  furnished  with  beards  or 
wings,  may  be  brought  from  an  immence  distance. 
The  fleabane  of  Canada  has  only  lately  been  found  in 
Europe;  and  Linnseus  supposes  that  it  has  been  trans- 
ported from  America,  by  the  very  light  downy  plumes 
with  which  the  seed  is  provided. 

In  feeding  cattle  with  green  food  there  are  many 
advantages  in  soilings  or  supplying  them  with  food, 
where  their  manure  is  preserved,  out  of  the  fieldj  the 


•  The  appearance  of  seeds  in  places  where  their  parent  plants  are  not  found 
may  be  easily  accounted  for  from  this  circumstance,  and  other  circumstances.  Many 
seeds  are  carried  from  island  to  island  by  currents  in  thesea,  and  are  defended  by 
their  hard  coats  from  the  immediate  action  of  the  water.  West  Indian  seeds  (of 
this  description}  are  often  found  on  our  coasts,  and  readily  germinate;  their  l«ng 
voyage  having  been  barely  sufficient  to  afford  the  cotyledon  its  due  proportion  of 
moisture.  Other  seeds  are  carried  indigested  in  the  stomach  of  birds,  and  suppli- 
ed with  food  at  the  moment  of  their  deposition.  The  light  seeds  of  the  mosses 
and  lichens,  probably  float  in  every  part  of  the  atmosphere,  and  abound  on  the 
snrffvce  of  the  sea. 


t  326  ] 

plants  are  IcvSs  injured  v;hen  cut,  than  when  torn  or 
jagged  with  the  teeth  of  the  cattle,  and  no  food  is 
wasted  by  being  trodden  down.  They  are  likewise 
obliged  to  feed  without  making  selection;  and  in  con- 
sequence the  whole  food  is  consumed:  the  attachment, 
or  dislike  to  a  particular  kind  of  food  exhibited  by  ani- 
mals, offers  no  proof  of  its  nutritive  powers.  Cattle 
at  first,  refuse  linseed  cake,  one  of  the  most  nutritive 
substances  on  which  they  can  be  fed.*^ 


•  For  the  following  observations  on  the  selection  of  different  kinds  of  com- 
niOB  food  by  sheep  and  cattle,  1  am  obliged  to  Mr,  George  Sinclair. 

"  Lolium  pereHne,ryt  gTAii.  Sheep,  eat  this  grass  when  it  is  in  the  early 
stage  of  its  growtl^  in  preference  to  most  others;  bat  after  the  seed  appro  iches  to- 
wards perfection,  they  leave  it  for  almost  any  other  kind.  A  field  in  the  Park  of 
"Woburn  was  laid  down  in  two  eqoal  parts,  one  part  wirh  rye  grass  and  white  clo- 
ver, and  the  other  part  with  cock's-foot  and  red  clover:  from  the  spring  till  mid- 
summer the  sheep  kept  almost  constantly  on  the  rye  grass;  but  ifter  that  time 
they  left  it,  and  adhered  with  equal  constancy  to  the  eock's-foot  during  there* 
maiiider  of  the  season. 

Dactyli s  gemerata,  coc'k's'foot.  Oxen,  horses,  and  sheep,  eat  this  grass  readi- 
ly. The  oxen  continue  to  eat  the  straws  and  flowers,  from  the  time  of  flowering, 
till  the  time  of  perfecting  the  seed;  this  was  exemplified  in  a  striking  manner  in 
the  field  before  alluded  to.  The  oxen  generally  kept  to  the  cock'srfoot  and  red 
clover,  and  the  sheep  to  the  rye-grass  and  white  clover.  In  the  experiments  pub- 
lished  in  the  Amoenitates  Academic*,  by  the  pupils  of  Linnaeus,  it  is  asserted, 
that  this  grass  is  rejected  by  oxen;  the  above  fact,  however,  is  in  contradiction 
of  it. 

Aloptcurui  pratcHsis,  meadow  fox-tail.  Sheep  and  horses  seem  to  have  a 
greater  relish  fof  this  grass  than  oxen.  It  delights  in  a  soil  of  intermediate  quality 
as  to  moisture  and  dryness,  and  is  very  productive.  In  the  water-meadow  at 
Priestley,  it  constitutes  a  considerable  part  of  the  produce  of  that  excellent  mea- 
dow. It  there  keeps  invariably  possession  of  the  top  of  the  ridges,  extending 
generally  about  six  feet  from  each  side  of  the  water  course;  the  space  below  that 
to  where  the  ridge  ends,  is  stocked  with  cock's-foot,  and  the  rough  stalked  mea- 
dow grass,  Feituca  pratensis,  Festuca  duriuscu/a,  Agrostis  itolonifera,  Agroitis  pat- 
ustrii,  and  sweet-scented  vernal  grass,  with  a  small  admixture  of  some  other 
Jkinds. 

Phleum  pratense,  meadow  cat  s-tail.  This  grass  is  eaten  without  reserve,  by 
©■Xen,  sheep,  and  horses.     Dr.  Pulteney  laysj  that  it  is  disliked  by  sheep;  bat  in 


C  327  ] 

When  food  artificially  composed  is  to  be  given  to 
cattle,  it  vshould  be  brought  as  nearly  as  possible  to  the 
state  of  natural  food.     Thus,  when  sugar  is  given  to 


pastures  where  it  abounds,  it  does  not  appear  to  be  rejected  by  these  animals;  but 
eaten  in  common  with  such  others  as  are  growing  with  it.  Hares  are  remarkably 
fond  of  it.  The  Phkum  nodosum,  Phieum  a/pinum,  Poafertilis,  and  Poa  compressa, 
were  left  untouched,  although  they  were  closely  adjoining  to  it.  It  seems  to  at- 
tain the  greatest  perfection  in  a  rich  deep  loam, 

Agro$tis  stolonifera,  florin.  In  the  experiments  detailed  in  the  Araocnitates 
Academicae,  it  is  said,  that  horses,  sheep,  and  oxen,  eat  this  grass  readily.  On  the 
Duke  of  Bedford's  farm  at  Maulden,  florin  hay  was  placed  in  the  racks  before  , 
horses  in  small  distinct  quantities;  alternately  with  common  hay;  but  no  decided 
preference  for  either,  was  manifested  by  the  horses  in  this  trial.  But  that  cows 
and  horses  prefer  it  to  hay,  when  in  a  green  state,  seems  fully  proved  by  Dr. 
Richardson  in  his  several  publications  on  Fiorin;  and  of  its  productive  powers  in 
England  (which  has  been  doubted  by  some,)  there  are  satisfactory  proofs.  Lady 
Hardwicke  has  given  an  account  of  a  trial  of  this  grass;  wherein  24  milch  cows, 
and  one  young  horse,  besides  a  nurabeu  of  pigs,  were  kept  a  fortnight  on  the  pro- 
duce of  one  acre. 

Poa  trivialis,  rough-stalked  meadow.  Oxen,  horses,  and  sheep,  eat  this 
grass  with  avidity.  Hares  also  eat  it;  but  they  give  a  decided  preference  to 
the  smoothed-stalked  meadow  grass,  to  which  it  is,  in  many  respects,  nearly 
allied. 

Port  j>ra/«Mj/5,  Bmooth-stalked  meadow  grass.  Oxen  and  horses,  are  observed 
to  eat  this  grass  in  common  with  others;  but  sheep  rather  prefer  the  hard  fescue, 
and  sheeps'  fescue  which  affect  a  similar  soil.  This  species  exhausts  the  soil  In  a 
greiter  degree,  than  almost  any  other  species  of  grass;  the  roots  being  numerous, 
and  powerfully  creeping,  Secome  in  two  or  three  years  completely  matted  toge- 
ther; the  produce  diminishes  as  this  takes  place.  It  grows  common  in  some 
meadows,  dry  ba.iks,  and  even  on  walks. 

Cynosurus  cristatus,  crested  dog's-tail  grass.  The  South  Down  sheep,  and 
deer,  appear  lo  be  rcniirkably  fond  of  this  grass:  in  some  parts  of  Woburn  Park: 
this  grass  fbrms  the  principal  part  of  the  herbage  on  which  these  animals  chiefly 
browse;  while  another  part  of  ihe  Park;  that  contains  the  Agrostis  capiliaris, 
Agrostis pumilis,  Feituca  ovina,  Festuca  duriuscula,  and  Festuca  cambrica,  is  seldom 
touched  by  them;  but  the  Welch  bref^d  of  sheep  almo'st  constantly  browse  upon 
these,  and  neglect  the  rywo^Mrw*  criitatus,  Lcliutn  perenne,  Tini  Poa  trivialis, 

Agrostis  vulgarii  (capilfarii  Linn.),  fine  bent;  common  bent.  This  is  a  very 
common  grass  on  all  poor  dry  sandy  soils.  It  is  not  palatable  to  cattle,  as  they 
never  eat  it  readily,  if  any  other  kinds  be  within  their  reach.  The  Welch  sheep, 
however,  prefer  it,  as  1  before  observed;  and  it  is  singular,  th  t  'hose  sheep 
being  bred  in  the  park,  when  some  of  the  best  grasses  are  equally  within  their 


c 


328 


them,  some  dry  fibrous  matter  should  be  mixed  with 
it  such  as  chopped  straw,  or  dry  withered  grass,  in  or- 
der that  the  functions  of  the  stomach  and  bowels  may 


reacli,  should  still  prefer  those  grasses  which  naturally  grow  on  the  Welch  moun- 
tains: it  seems  to  argue  that  such  a  preference  b  the  effect  of  some  other  cause, 
chan  that  of  habit. 

Festuca  ovina.  sheeps*  fescue.  All  kinds  of  cattle  relish  this  grass;  but  it  ap- 
pears from  the  trial  that  has  been  made  with  it  on  clayey  soils,  that  it  continues 
but  a  short  time  in  possession  of  such,  being  soon  overpowered  by  the  more  luxuri- 
ant kinds.  On  dry  shallow  soils  that  are  incapable  of  producing  the  larger  sorts 
this  should  form  the  principal  crop,  or  rather  the  whole;  for  it  is  seldom  or  ever,  in 
its  natural  state,  found  intimately  mixed  with  others;  but  by  itself. 

Festuca  duriufcula,h3rd  fescue  grasss.  This  is  certainly  one  of  the  best  of  the 
dwarf  sorts  of  grasses.  It  is  grateful  to  all  kutds  of  cattle;  horses  are  very  fond  of 
it;  they  cropped  it  close  to  the  roots,  and  neglected  the  Festuca  ovina,  and  Festuca 
rubra,  which  were  contiguous  to  it.  It  is  present  in  most  good  meadows  and 
pastures. 

Festuca  /)ra^en*/j,  ro  eadow  fescue.  This  grass  seldom  absent  from  rich  mea- 
dows and  pastures;  it  is  observed  to  be  highly  grateful  to  oxen,  sheep,  and  horses, 
particularly  the  former.  It  appears  to  grovr  most  luxuriantly  when  combined 
with  the  hard  fescue,. and  Poa  trivialis. 

Avena  eliaior,  tall  oat  grass.  This  is  a  very  productive  grass,  frequent  in 
meadows  and  pastures,  but  is  disliked  by  cattle,  particularly  by  horses;  this,  per- 
fectly, agree*  with  the  small  portion  of  nutritive  which  matter  it  affords.  It 
seems  to  thrive  best  on  a  strong  tenacious  clay. 

Avena  fiavescens,  yellow  oat-grass.  This  grass  seems  partial  to  dry  soils,  and 
meadows,  and  appears  to  be  eaten  by  sheep  and  oxen,  equally  with  the  meadow 
barley,  crested  dog's-tail,  and  sweet-scented  vernal  grasses  which  naturally  grow 
in  company  with  it.  linearly  doubles  tlie  quantity  of  its  produce  by  the  appli- 
cation of  calcareous  manure. 

Holcuilanatus,  meadow  soft  gra«s.  This  is  a  very  common  grass,  and  grows 
on  all  soils,  from  the  richest  to  the  poorest.  It  affords  an  abundance  of  seed, 
which  is  light,  and  easily  dispersed  by  the  wind.  It  appears  to  be  generally  disli- 
ked by  all  sorts  of  cattle.  The  produce  is  not  so  great  as  a  view  of  it  in  fields 
would  indicate;  but  being  left  almost  entirely  untouched  by  cattle,  it  appears  as 
the  most  productive  part  of  the  herbage.  The  hay  which  is  made  of  it,  from  the 
number  of  downy  hairs  which  cover  the  surface  of  the  leaves,  is  soft  and  spongy, 
and  disliked  by  cattle  in  general. 

Anthnxanthum  odratum,  sweet-scented  vernal  grass.  Horses,  oxen,  and  sheep, 
eat  this  grass;  though  in  pastures  where  it  is  combined  with  the  meadow  fox- 
tail, and  white  clover,  co«|L'8-toot,  rough-stalked  meadow,  ir  is  left  untouched, 
from  which    it  would   seem  unpalatable  to  cattle.     Mr.  GrantjOf  Leighton,    laid 


.         L  S29         J 

be  performed  in  a  natural  manner.  The  principle  is  the 
same  as  that  of  the  practice  alluded  to  in  the  Third 
Lecture,  of  giving  chopped  straw  with  barley. 

In  washing  sheep,  the  use  of  water  containing 
carbonate  of  lime  should  be  avoided;  for  this  substance 
decomposes  the  yolk  of  the  wool,  which  is  an  animal 
soap,  the  natural  defence  of  the  wool;  and  wool  often 
washed  in  calcareous  water,  becomes  rough  and  more 
brittle.  The  finest  wool,  such  as  that  of  the  Spanish 
and  Saxon  sheep,  is  most  abundant  in  yolk.  M.  Van- 
quelin  has  analysed  several  different  species  of  yolk, 
and  has  found  the  principal  part  of  all  of  them  a  soap, 
with  a  basis  of  potassa,  (I.  e.  a  compound  of  oily  mat- 
ter and  potassa),  with  a  little  oily  matter  in  excess.  — 
He  has  found  in  them  likewise,  a  notable  quantity  of 
acetate  of  potassa,  and  minute  quantities  of  carbonate 
of  potassa  and  muriate  of  potassa,  and  a  peculiar  odor, 
ous  animal  matter. 

M.  Vanquelin  states,  that  he  found  some  speci- 
mens of  wool  lose  as  much  as  45  per  cent,  in  being 
deprived  of  their  yolk;  and  the  smallest  loss  in  his 
experiments  was  35  per  cent. 

The  yolk  is  most  useful  to  the  wool  on  the  back 
of  the  sheep,  in  cold  and  wet  seasons;  probably  the 


down  one  half  a  field  of  a  considerable  extent  with  this  grass,  combined  with 
white  clover.  The  other  half  of  the  field  with  fox-tail  and  red  clover.  The  sheep 
would  not  touch  the  sweet-scented  vernal,  but  kept  constantly  upon  the  fox-tail 
The  writer  of  this,  saw  the  field  when  the  grasses  were  in  the  highest  state 
of  perfection:  and  hardly  any  thing  could  be  more  satisfactory.  Equal  quanti- 
ties of  the  seeds  of  white  clover,  were  sown  with  each  of  the  grasses,  but  from 
the  dwarf  nature  of  the  sweet-scented  venial  grass,  the  clover  mixed  with  it 
had  attained  to  greater  luxuriance,   than  that  mixed  with  the  meadow  fox-tail. 

u2 


#  (  330  ) 

application  of  a  little  soap  of  potassa,  with  excess  of 
grease  to  the  sheep  brought  from  warmer  climates  in 
our  winter,  that  is,  increasing  their  yolk  artificially^ 
might  be  useful  in  cases  where  the  fineness  of  the 
wool  is  of  great  importance.  A  mixture  of  this  kind 
is  more  conformable  to  nature,  than  that  ingeniously 
adopted  by  Mr,  Bakewell;  but  at  the  time  his  labours 
commenced,  the  chemical  nature  of  the  yolk  was  un- 
known. 


331 


I  have  now  exhausted  all  the  subjects  of  discus- 
sion, which  my  experience  or  information  have  been 
able  to  supply  on  the  connection  of  chemistry  with 
agriculture. 

I  venture  to  hope,  that  some  of  the  views  brought 
forward,  may  contribute  to  the  improvement  of  the 
most  important  and  useful  of  the  arts. 

I  trust  that  the  enquiry  will  be  pursued  by 
others;  and  that  in  proportion  as  chemical  philosophy 
advances  towards  perfection,  it  will  afford  new  aids  to 
agriculture. 

There  are  sufficient  motives  connected  with  both 
pleasure  and  profit,  to  encourage  ingenius  men  to  pur-- 
sure  this  new  path  of  investigation.  Science  cannot 
long  be  despised  by  any  persons  as  the  mere  specula- 
tion of  theorists;  but  must  soon  be  considered  by  all 
ranks  of  men  in  its  true  point  of  view,  as  the  refine-, 
ment  of  common  sense,  guided  by  experience,  gradu- 
ally substituting  sound  and  rational  principles,  for 
vague  popular  prejudices. 

The  soil  offers  inexhaustible  resources,  which 
when  properly  appreciated  and  employed,  must  in- 
crease our  wealth,  our  population,  and  our  physical 
strength. 

We  possess  advantages  in  the  use  of  machinery, 
and  the  division  of  labour,  belonging  to  no  other  na- 
tioiK     And  the  same  energy  of  character,  the  same  ex„ 


(  332  ) 

tent  of  resources  which  have  always  distinguished  the 
people  of  the  British  Islands,  and  made  them  excel  in 
arms,  commerce,  letters,  and  philosophy,  apply  with 
the  happiest  effect  to  the  improvement  of  the  cultiva- 
tion of  the  earth.  Nothing  is  impossible  to  labour, 
aided  by  ingenuity.  The  true  objects  of  the  agricul- 
turist are  likewise  those  of  the  patriot.  Men  value 
most  what  they  have  gained  with  effort;  a  just  confi- 
dence in  their  own  powers  results  from  success;  they 
love  their  country  better,  because  they  have  seen  it  im- 
proved by  their  own  talents  and  industry;  and  they 
identify  with  their  interests,  the  existence  of  those  in- 
stitutions which  have  afforded  them  security,  inde- 
pendence,  and  the  multiplied  enjoyments  of  civilized 
life. 


APPENDIX. 


AN 
ACCOUNT  OP  THE  RESULTS 

OF 

EXPERIMENTS  ON  THE  PRODUCE 

AND 

NUTRITIVE  QUALITIES 

OF 

DIFFERENT  GRASSES,  AND  OTHER  PLANTS, 

USED  AS  THE  FOOD    OF  ANIMALS. 

INSTITUTED   BY 

JOHN,  DUKE  OP  BEDFORD. 


BOOKS  QUOTED  IN  THE  FOLLOWING  PAGES, 

Curt.  Lond — Flora  Londinensis.    By  William  Curtis,  2  vols. 

London  1798,  fol. 
Fli  Dan.-?-Flora  Danica,  or  Icones  Plantarum  sponte  nascen- 

tium  in   Rcgnis  Daniae  et  Norvegiae,  editse  a 

Ge  iEder.    Hafniae  1761,  fol. 
Engl.  Bot.— English  Bontany,  by   J.  E.  Smith,  M.  D ;  the 

Figures  by  J.  Sowerby.     London  1 790,  8vo. 
W.  B.— Botahical  Arrangements.    By  Dr.  Withering.    LoH' 

don  1801,  4  vol. 
Huds. — Hudsoni  Flora  Anglica,  1778,  vol.  ii. 
Host.  G.  A. — Nic.    Thomae    Host  Icones  et   Descriptiones 

Graminum  Austriacorum,  vol.  i.— iii.  Vindo- 

bonae,  1801,  fol. 
Hort.  Kew.«— Hortus  Kewensis.    By  W.  J.  Alton,  vol.  i.  Lon- 
don 1810. 


Introduciion  by  the  Editor. 

Of  the  215  proper  grasses  which  are  capable  of 
being  cultivated  in  this  climate  two  only  have  been 
employed  to  any  extent  for  making  artificial  pastures, 
rye  grass  and  cock's  foot  grass  j  and  their  application 
for  this  purpose  seems  to  have  been  rather  the  result 
of  accident,  than  of  any  proofs  of  their  superiority 
over  other  grasses. 

A  knowledge  of  the  comparative  merits  and 
Value  of  all  the  different  species  and  varieties  of  grasses 
cannot  fail  to  be  of  the  highest  importance  in  practical 
agriculture.  The  hope  of  obtaining  this  knowledge 
was  the  motive  that  induced  the  Duke  of  Bedford  to 
institute  this  series  of  experiments. 

Spots  of  ground,  each  containing  four  square 
feet,  in  the  garden  at  Woburn  Abbey,  were  enclosed 
by  boards  in  such  a  manner  that  there  was  no  lateral 
communication  between  the  earth  included  by  the 
boards,  and  that  of  the  garden.  The  soil  was  re- 
moved in  these  inclosures,  and  new  soils  supplied  ; 
or  mixture  of  soils  were  made  in  them,  to  furnish  as 
far  as  possible  to  the  different  grasses  those  soils  which 
seem  most  favourable  to  their  growth ;  a  few  varieties 
being  adopted  for  the  purpose  of  ascertaining  the 
effect  of  different  soils  on  the  same  plant. 

The  grasses  were  either  planted  or  sown,  and 
their  produce  cut  and  collected  and  dried,  at  the  pro- 
per seasons,  in  summer  and  autumn,  by  Mr,  Sinclair,. 


[      iv.      3 

his  Grace's  gardener.  For  the  purpose  of  determin- 
ing as  far  as  possible  the  nutritive  powers  of  the 
different  species,  equal  weights  of  the  dry  grasses  or 
vegetable  substances  were  acted  upon  by  hot  water 
till  all  their  soluble  parts  were  dissolved  ;  the  solution 
was  then  evaporated  to  dryness  by  a  gentle  heat  in  a 
proper  stove,  and  the  matter  obtained  carefully  weigh- 
ed. This  part  of  the  process  was  likewise  conducted 
with  much  address  and  intelligence  by  Mr.  Sinclair, 
by  whom  all  the  following  details  and  calculations  are 
furnished. 

The  dry  extracts  supposed  to  contain  the  nutri- 
tive matter  of  the  grasses,  were  sent  to  me  for  chemi- 
cal examination.  The  composition  of  some  of  them 
is  stated  in  the  last  table  of  Chap.  III.  I  shall  offer  a  few 
chemical  observations  on  others  at  the  end  of  this 
Appendix.  It  will  be  found  from  the  general  conclu- 
sions, that  the  mode  of  determining  the  nutritive 
power  of  the  grasses,  by  the  quantity  of  matter  they 
contain  soluble  in  water,  is  sufficiently  accurate  for  all 
the  purposes  of  agricultural  investigation. 


Details  of  Experiments  on  Grasses.  £y  George  Sin- 
clair, Gardener  to  his  Grace  the  Duke  of  Bed- 
ford, and  Corresponding  Member  of  the  Horticultural 
Society  of  Edinburgh, 


L  AnthoxanthuM  odoratum,     Engl.  Bot.  647. — Curt, 
Lond. 

Sweet-scented  vernal  grass.  Nat.  of  Britain. 
At  the  time  of  flowering,  the  produce  from  the  space 

of  an  acre  equal  to       ,00u09 1827364  of  a  brown 

sandy  loam  with  manure,  is 

oz.  or  lbs.  per  acre 

Grass  11  oz.  8  dr.*  The  produce  per  acre      125235    0  ~  7827    3    0 
80  dr.  of  grass  weigh  when  dry    21  1-2  dr.-% 

I'he  producf  of  the  space,  ditto    49.  1  7-10  3  ^^^^^    ^  ~"  ^^^^    ^    ^ 
The  weight  lost  by  the  produce  of  one  acre  in  drying  5723  10    0 

64  dr  of  grass  afford  of  nutritive  matter  1  dr.  "> 
The  produce  of  the  space,  ditto        2.  3  5-103    ^^^^  ^^  "*"  ^^^      ^  ^^ 

At  the  time  the  seed  is  ripe  the  produce  is 

Grass,  9  oz.     The  produce  per  acre        -  98010    0  —  6125  10    0 

80  dr.  of  grass  weigh  when  dry  24  dr.    ^ 

The  produce  of  the  space,  ditto  43.1-163^^^^^    0  —  1837  11    0 

The  weight  lost  by  the  produce  of  one  acre  in  drying         —  4287  15    0 

64  dr.  of  grass  afford  of  nutritive  matter  3. 1  dr.  "> 

The  produce  of  the  space  ditto  7. 1 1-43  ^^^^  ^^  —    311    1    1 

The  weight  of  nutritive  matter  which  is  lost  by  taking-^ 
the  crop  at  the  time  the  grass  is  in  flower,  exceed.  C  188  12    4 

ing  half  of  its  value j 

The  proportional  value  which  the  grass  at  the 
time  of  flowering  bears  to  that  at  the  time  the  seed  is 
ripe,  is  as  4  to  13. 


•  The  weight  is  avoirdupoisa ;  lbs.  pounds,  oz.  ounces,  dr.  drachms.  The 
v/eights  not  named  are,  quarters  of  drachms,  and  fractions  of  quarters  of  drachms  f 
thus  7.  1  1-4  means  7  drachms  i  quarter  of  a  drachm  and  1-4  of  a  quarter. 


VI.  APPENDIX. 

The  latter-math  produce  is         oz.      or  ibs.  per  acre 

Grass,  10  oz.-    The  produce  per  acre  108900    0  —  6806    4    0 

64dr.ofgr;issaffordofnutiitivemHtter,  2.  1  dr.  3828    8  —    239    4    8 

The  proportional  value  which  the  grass  of  the 
latter-math  bears  to  that,  at  the  time  the  seed  is  ripe, 
is  nearly  as  9  to  13. 

The  smallness  of  the  produce  of  this  grass  ren- 
ders it  improper  for  the  purpose  of  hay;  but  its  early 
growth,  and  the  superior  quantity  of  nutritive  matter 
w^hich  the  latter-math  affords,  compared  with  the 
quantity  affoi'ded  by  the  grass  at  the  time  of  flowering, 
causes  it  to  rank  high  as  a  pasture  grass,  on  such  soils 
as  are  well  fitted  for  its  growth ;  such  are  peat-bogs, 
and  lands  that  are  deep  arid  moist. 

I.I.  Holcus  odoratus.  Host.  G.  A,  Growing  in  woods. 

Sweet  scented  soft  grass.    Nat.  of  Germany.  Flo. 

Ger. — H.  Borealis.  Growing  in  moist  meadows. 

At  the  time  of  flowering,  the  produce  from  a  rich 

sandy  loam  is 

oz.  or  lbs,  per  acre 

Grass,  14  oz.    The  produce  per  acre  152460    0  —  9528  12    0 

80  dr.  of  grass  weigh  when  dry    20,  2  dr.  "i 

The  produce  of  the  space,  ditto    57  1  3-5  5     ^^^^^  ^^  ~  ^^^^  ^^  ^^ 
The  weight  lost  by  the  produce  of  one  acre  in  drying  7087    0    2 

64  dr,  of  grass  afford  of  nutritive  matter  4. 1  dr.  ■> 
The  produce  of  the  space,  ditto  14  3  1-23  ^^^^^  ^^  ""  ^^^  ^^    ^ 

At  the  time  the  seed  is  ripe  the  produce  is 

Grass,  40  oz.    The  produce  per  acre  435600    0  —  27225    0    0 

64  dr,  of  grass  weigh  when  dry        28  dr.-^ 

The  produce  ofthe  space,  ditto      224  dr. 5    ^^^^^^    0  —  9528  12    0 

The  weight  lost  by  the  produce  of  one  acre  in  drying  17696    4    0 

64  dr..  of  grass  a/ford  of  nutritive  matter  5. 1  dr.-> 

The  produce  of  the  space,  ditto  52-  2  dr.5  ^^^^^  ^^  ~  ^^^^    ^  ^ ^' 

The  weight  of  nutritive  matter  which  is  lost  by  taking  the 
crop  at  the  time  the  grass  is  in  flower,  being  more  than 
halfof  its  valu'  1600    8  10 


APPENDIX.  vii. 

The  proportional  value  which  the  grass  at  the 
time  of  flowering  bears  to  that  at  the  time  the  seed  is 
ripe,  is  as  17  to  21. 

The  produce  of  latter-math  is  oz.       or  lbs.  per  acre 

Grass,  25  oz.     (he  produce  per  acre  272250    0  —  17015  10    0 

64  dr.  of  grass  iiff ord  of  nutritive  matter  4. 1  dr.  18079    1  —     1129  15     1 

The  grass  of  the  latter-math  crop,  and  of  the 
crop  at  the  time  of  flowering,  taking  the  whole  quantity, 
and  their  relative  proportions  of  nutritive  matter,  are 
in  value  nearly  as  6  to  10:  the  value  of  the  grass  at 
the  time  the  seed  is  ripe,  exceeds  that  of  the  latter-math, 
in  proportion  as  21  to  17. 

Though  this  is  one  of  the  earliest  of  the  flower- 
ing grasses,  it  is  tender,  and  the  produce  in  the  spring 
is  inconsiderable.  If,  however,  the  quantity  of  nutri- 
tive matter  which  it  affords,  be  compared  with  that  of 
any  of  those  species  which  flower  nearly  at  the  same 
time,  it  will  be  found  greatly  superior.  It  sends  forth 
but  a  small  number  of  flower  stalks,  which  are  of  a 
slender  structure  compared  tm  the  size  of  the  leaves. 
This  will  account  in  a  great  measure  for  the  equal 
quantities  of  nutritive  matter  afforded  by  the  grass  at 
the  time  of  flowering,  and  the  latter-math. 

III.  Cynosurus  caruleus.  Engl.  Bot.  1613.  Host. 
G.  A.  2.  t.  98.  Blue  moor-grass.  Nat.  of 
Britain.     Sesleria  cserulea. 

At  the  time  the  seed  is  ripe  the  produce  from  a 
light  sandy  soil  is 

oz.  or  lbs.  per  acre 

Grass,  10  oz.    The  produce  per  acre  108900    0  —  6806    4    3 

6:4  dr.  of  grass  afford  of  nutritive  matter  3  3  dr.  6380  13  —    398  12  13 


VIII.  APPENDIX. 

The  produce  of  this  grass  is  greater  than  its  ap- 
pearance would  denote;  the  leaves  seldom  attain  to 
more  than  four  or  five  inches  in  length,  and  the  flower 
stalks  seldom  arise  to  more.  Its  growth  is  not  rapid 
after  being  cropped,  nor  does  it  seem  to  withstand 
the  effects  of  frost,  which  if  it  happen  to  be  severe 
and  early  in  the  spring,  checks  it  so  much  as  to  pre- 
vent it  from  flowering  for  that  season;  otherwise  the 
quantity  of  nutritive  matter  which  the  grass  affords 
(for  the  straws  are  very  inconsiderable,)  would  rank 
it  as  a  valuable  grass  for  permanent  pasture. 

IV.  Alopecurus  pratensis.    Curt.  Lond.  Alo.  myosur- 
oides.     Meadow  foxtail-grass.      Nat.  of  Britain. 
Engl.  Bot.  848. 
At  the  time  of  flowering,  the  produce  from  a 

clayey  loam  is  oz.  or  lbs.  per  acre 

Grass,  30  oz,  >  1  he  produce  per  acre  326700    0  —  20418  12    0 

80  dr.  of  erass  weicrh  when  dry         24  dr.  7 

A         c.u  A. I        o.«.„C    98010    0—    6125  10    0 

1  he  produce  of  the  space,  ditto       336  dr.  3 

The  weight  lost  by  the  produce  of  one  acre  in  drying  14293    2    0 

64  dr.  of  grabs  afford  of  nut '-itivjp  matter  1  2  dr.  ) 

The  produce  of  the  space,  ditto  llldr.V^^^^""    ^'^    ^^    ^ 

The  produce  from  a  sandy  loam  is 

Grass,  12  oz.  8  dr.    The  produce  per  acre        136125    0  —  8507  13    0 

80  dr.  of  grass  weigh  when  dry  24  dr.  ^ 

The  produce  of  the  space,  ditto  60  dr.  3   ^^^'^'^    9  —  2552    5    8 

64  dr  .of  grass  afford  of  nutritive  matter  1  dr.  ^ 

The  produce  of  the  space,  ditto  3  01-2  S    ^^^^  ^^  ""    ^^^  ^^  ^^ 

At  the  time  the  seed  is  ripe,  the  produce  from 
the  clayey  loam  is 

Grass,  19  oz.    The  produce  per  acre  206910    0  —  12931  14    0 

80  dr.  of  grass  weigh  when  dry  36  dr.  ^ 

The  produce  of  the  space,  ditto      136  3  1-5  3   ^^^^^    ^  ^  ^^^^    ^    * 
The  weight  lost  by  the  produce  of  one  acre  in  drying  7111    8  14 

64  dr.  of  grass  afibrd  of  nutritive  matter  1  1  dr.  ^  . 

Tlie  produce  of  the  space,  ditto  9.  975  V  ^^^    4—461    0 


APPENDIX.  IX. 

The  weight  of  nutritive  matter  which  is  lost  by  leavln«:r  the 
crop  till  the  seed  be  ripe,  being  one  twenty-fifth  part  of 
its  value  ^7    8  11 

The  proportional  value  which  the  grass  at  the 
time  of  flowering,  bears^  to  that  at  the  time  the  seed  is 
ripe,  is  as  6  to  9. 

The  latter-math  produce,  from  the  clayey  loam  is 

oz.        or  lbs.  per  acre 
Grass,  12  oz.    The  produce  per  acre  130680    0  —  8167    8    0 

64  dr.  of  ffrass  afford  of  nutritive  matter  2  dr.  7 

n^u  1  i-<.  r..  ^^aA    4083  12—    255     3  12 

The  pr  duce  of  the  space,  ditto  o  clr,  3 

The  proportional  value  which  the  whole  of  the 
latter- math  crop  bears  to  that  at  the  time  the  seed  is 
ripe,  is  as  5  to  9,  and  to  that  at  the  time  flowering, 
proportionably  as  13  to  24. 

The  above  statement  clearly  shews  that  there  is 
nearly  three-fourths  of  produce  greater  from  a  clayey 
loam  than  from  a  sandy  soil,  and  the  grass  from  the  lat- 
ter is  comparatively  of  less  value,  in  proportion  as  4 
to  6.  The;  straws  produced  by  the  sandy  soil  are  defi- 
cient in  number  and  in  every  respect  less  than  those 
from  the  clayey  loam;  which  will  account  for  the  un- 
equal quantities  of  nutritive  matter  afforded  by  them; 
but  the  proportional  value  in  which  the  grass  of  the 
latter-math  exceeds  that  of  the  crop  at  the  time  of 
flowering,  is  as  4  to  .S;  a  difference  which  appears 
extraordinary,  when  the  quantity  of  flower-stalks 
which  are  in  the  grass  at  the  time  of  flowering  is 
considered.  In  the  Anthoxanthum  odoratum  the  pro- 
portional difference  between  the  grass  of  these  crops 
is  still  greater,  nearly  as  4  to  9 ;  in  the  Poa  pratensis 
they  are  equal;  but  in  all  the  latter  flowering  grasses 
experimented  upon,   the  flowering  straws  of  which 

b 


X.  AlPPENblX. 

resemble  those  of  the  Alopecurus  praiensts  or  Anthosc- 
anthum  odoratum^  the  greater  proportional  value  is 
always  on  the  contrary  found  in  the  grass  of  the 
flowering  crop.  Whatever  the  cause  may  be,  it  is 
evident  that  the  loss  sustained  by  taking  the  crops  of 
these  grasses  at  the  time  of  flowering  is  considerable. 

V.  Alopecurus  alpinus.     Engl.  Bot.  1126. 
Alpine  fox-tail  grass.     Nat.  of  Scotland. 

At  the  time  of  flowering  the  produce  from  a  sandy 
loam  with  a  small  portion  of  manure,  is 

oz.  or  lbs.  per  acre 

Grass,  8  oz.  The  produce  per  acre  87120  0  —  5445  5  0 
60  dr.  of  grass  weigh  when  dry    16  dr.      ^ 

The  produce  ofthe  space,  ditto   34  2-16   3     ^^^^^  0  —  1452  0  0 

The  weight  lost  by  the  produce  of  one  acre  in  drying  S993  5  0 
64  dr.  of  grass  afford  of  nutritive  matter      1  dr.  ^ 

The  produce  of  the  space,  ditto                  2  dr.j   ^^^^    4—85  1  4 

VI.  Foa  alpina.    Engl.  Bot.  1003.    Flo.  Dan.  107. 
Alpine  meadow  grass.     Nat.  of  Scotland. 

At  the  time  of  flowering,  the  produce  from  a  light 
sandy  loam,  is 

Grass,  8  oz.    The  produce  per  acre  87120    0  —  5445    0    0 

64  dr.  of  grass  afford  of  nutritive  matter,  1. 2  dr.  2041  14  —    127    9  14 

VII.  Avma  pubescens.    Engl.  Bot.  1640.     Host.  G. 
A.  2,  t.  SO.    Downy  oat  grass.    Nat.  of  Britain. 

At  the  time  of  flowering,  the  produce  from  a 
rich  sandy  soil,  is 

Grass,  23  oz.    The  produce  per  acre              250470  0  —  15654  6  0 

80dr.  ofg-rass  wieighwhen  dry            SOdr.^    ^  ^^  ^        ,„^^  ^  . 

r^t.  /  r.i,  A'Jl  too.  ^93926  0—  5870  6  4 
The  produce  ofthe  space,  ditto         lo8  dr.  3 

The  weight  lost  by  the  produce  of  one  acre  in  drying  9783  15  12 

64  dr.  of  grass  afford  of  nutritive  matter  1.  2  dr.  1  ^ra  14.    ^ 

The  produce  of  the  space,  ditto  8.2  2-16  $  ^°"°   ^ ""  ^^^  ^^ 


APPENDIX.  xr. 

At  the  time  the  seed  is  ripe,  the  produce  is 

oz.  or  lbs.  per  acre 

Grass,  10  oz.    The  produce  per  acre  108900    0  —  6806    4    0 

80  dr.  of  grass  weigh  when  dry  16  dr.7 

The  produce  of  tlie  space,  ditto  32  dr. 3  ^^''^^    0  —  1361    4    0 

The  weight  lost  by  the  produce  of  one  acre  in  drying         —  5445    0    0 
64  dr.  ofgrass  afford  ofnutritive  matter     2dr.>^ 

The  produce  ofthe  space  ditto  5  dr.  5   ^^^^    ^  ""    212  11    0 

The  weij^ht  of  nutritive  matter  which  is  lost  by  leaving  the  crop  till  the 

seed  be.  ripf,  bein.'  more  th  .11  half  of  its  value        -  154    6    3 

The  proportional  value  which  the  grass,  at  the 
time  of  flowering,  bears  to  that  at  the  time  the  seed  is 
ripe,  is  as  6  to  8  • 

The  produce  of  latter-math  is 

Grass,  10  oz      i  he  produce  p  r  acre  108900    0  —  6806    4    0 

64dr.ofi;ias;  iffwrd  of  nutritive  m^itter  2  dr.        3403    2—    212  11    0 

The  proportional  value  which  the  grass  at  the 
time  of  flowering  bears  to  that  of  the  latter-math,  is  as 
6  to  8.  The  grass  of  the  seed-crop^  and  that  of  the 
latter-math,  are  of  equal  value. 

The  downy  hairs  which  cover  the  surface  of  the 
leaves  of  this  grass,  when  growing  on  poor  light  soils, 
almost  entirely  disappear  when  it  is  cultivated  on  a 
richer  soil.  It  possesses  several  good  qualities  which  re- 
commend it  to  particular  notice  j  it  is  hardy,  early,  and 
more  productive  than  many  others  which  affect  simi- 
lar soils  and  situations.  Its  growth  after  being  cropped 
is  tolerably  rapid,  although  it  does  not  attain  to  a  great 
length  if  left  growing;  like  the  Poa  pratensis  it  sends 
forth  flower  stalks  but  once  in  a  season,  and  it  appears 
well  calculated  for  permanent  jpasture  on  rich  light 
soils. 


APPENDIX. 


VIII.  Poa  praiensis.  Curt  Lond.  Engl.  Bot.  1073. 
Smooth  stalked  meadow  grass,  Nat.  of  Britain. 
At  the  time  of  flowering,  the  produce  from  a  mix- 
ture of  bog-earth  and  clay,  is  oz.  or  Ibs.  per  acre 
Grass,  15  02.  s  lie  pr.iduce  pf-r  acre  163350  0  —  10209  6  0 
80  dr.  of  grass  weigh  when  dry       22.2  dr. 


The  produce  ofthe  space,  ditto      6r.2  dr.5     ^^^^^    ^  ~"    ^^'^^    ^  ^ 

The  weight  lost  by  the  produce  of  one  acre  in  drying             7337  15  13 
64  di".  of  grass  afford  of  nutritive  matter  1.3  dr."> 

The  produce  of  tbe  space,  ditto             6.2  1-165^^^^    2—279    2  9 

At  the  time  the  seed  is  ripe,  the  produce  is 

Grass,  12. 8  o%.    The  protiuce  per  acre  136125    0  —  85C7  13    0 

80  dr.  of  grass  weigh  wlien  dry  32  dr.? 

The  produce  ofthe  space,  do  80  dr.->  ^^^^    0—3403    2    0 

The  weight  lost  by  the  produce  of  one  acre  in  drying  5104  11     0 

64  dr.  of  grass  afford  of  nutritive  matter  1.2  dr.  7 

The  produce  of  the  space,  ditto  4.2  3-163^^^^    6—199    6    0 

The  weight  of  nutritive  matter  which  is  lost  hy  leaving  the 
crop  till  the  seed  be  ripe,  being  nearly  one  fourth  of  its 
value        -  ......  79  12    9 

The  produce  of  latter-math  is 

Grass,  6  oz.    I'he  produce  per  acre  65340    0  —  4083  12    0 

64  dr.  of  Grass  afford  of  nutritive  matter  1.3  dr.    1786  10 —    11110    0 

The  proportional  value  in  which  the  grass  of  the 
latter-math  exceeds  that  of  the  flowering  crop,  is  as 
6  to  7.  The  grass  of  the  seed  crop  and  that  of  the 
latter-math  are  of  equal  value, 

This  grass  is  therefore  of  least  value  at  the  time 
the  seed  is  ripe :  a  loss  of  more  than  one  fourth  of  the 
value  of  the  whole  crop  is  sustained  if  it  is  not  cut  till 
that  period:  the  straws  are  then  dry,  and  the  root 
leaves  in  a  sickly  decaying  state;  those  of  the  latter- 
math,  on  the  contrary,  are  luxuriant  and  healthy. 
This  species  sends  forth  flower-stalks  but  once  in  a 
season,  and  these  being  the  most  valuable  part  of  the 
plant  for  the  purpose  of  hay  j  it  will  from  this  circum- 


APPENDIX.  xirr. 

Stance,  and  the  superior  value  of  the  grass  of  the  latter- 
math,  compared  to  that  of  the  seed  crop,  appear  well 
adapted  for  permanent  pasture. 

IX.  Pod  carullea. — Var.   Poa  praiensis.     Engl.  Bot, 

1O04.  Poa  subcasrulea.  Short  blueish  meadow 
grass.  Nat.  of  Britain.  H.  Kew.  1 — 155.  Poa 
humilis. 

At  the  time  of  flowering,  the  produce  from  a  soil 
of  the  like  nature  as  the  preceding,  is 

oz.  or  lbs.  per  acre 

Grass,  11  oz.  The  produce  per  acre  119790  0  —  7486  14  0 
64  dr  of  grass  afford  of  nutritive  matter  2     dr.  1 

The  produce  of  the  space,  ditto  5. 2  dr.  5  ^"^^  ^  *"  2^3  15  0 
80  dr.  of  grass  weigh  when  dry      24  dr.       "^ 

The  produce  ofthe  space,  ditto       52.3  3-163    ^^^^^  ^  "*"  ^^"^^    ^  ^ 

The  weight  lost  by  the  produce  of  one  acre  in  drying  5240  13  0 

If  the  produce  of  this  variety  be  compared  with 
that  of  the  preceding  one,  it  will  be  found  less ;  nor 
does  it  seem  to  possess  any  superior  excellence.  The 
superior  nutritive  power  does  not  make  up  for  the 
deficiency  of  produce  by  80  lbs.  of  nutritive  matter 
per  acre. 

X,  Festuca  hordiformis,     Poa  hordiformis.     H.  Cant. 
Barley-like  fescue  grass.     Nat.  of  Hungary. 

At  the  time  of  flowering,  the  produce  from  a  sandy 
soil,  with  manure,  is 

Grass,  20  oz.    The  produce  per  acre               217800    0  —  13612    8  0 

80  dr.  of  grass  weigh  when  dry  24  dr.  > 

The  produce  of  the  space,  ditto            96dr.S^^^^^    0-4085  12  0 

The  weight  lost  by  the  produce  of  one  acre  in  drying             9528  12  0 

64  dr.  of  grass  afford  of  nutritive  matter  2. 1  dr.  "> 

The  produce  of  the  space,  ditto           11.  ldr.5   ''^^^   0-478    9  0 

This  is  rather  an  early  grass,  though  later  than 
any  of  the  preceding  species  5  its  foliage  is  very  fine, 


3CIV.  APPENDIX. 

resembling  the  F.  duriuscula,  to  which  it  seems  nearly 
allied,  differing  only  in  the  length  of  the  awns,  and  the 
glaucous  colour  of  the  whole  plant.  The  considera- 
ble produce  it  affords,  and  the  nutritive  powers  it  ap- 
pears to  possess,  joined  to  its  early  growth,  are  quali- 
ties which  strongly  recommend  it  to  further  trial. 
XL  Poa  trmalis.     Curt.  Lond.     Engl.  Bot.  1072. 

Host.  G.  A.  2.  t.  62.     Roughish  meadow  grass. 

Nat.  of  Britain. 
At  the  time  of  flowering,  the  produce  from  a  light 
brown  loam,  with  manure,  is  oz.       or  ibs.  per  acre 

Grass,  11  oz.    The  produce  per  acre               119790  0  —  7487  14  0 

80  dr.  of  grass  weigh  when  dry       24  dr.  ^ 

The  produce  ofthe  space,  ditto      54  3-163      ^^^^'^  0  —  2246    1  0 

The  weight  lost  by  the  produce  of  one  acre  in  drying  5240  13  0 

64  dr.  of  grass  afford  of  nutritive  matter  2  dr.> 

The  produce  of  the  space,  ditto           5.  2  dr. 5   '^'^^^  '' ""    233  15  7 

At  the  time  the  seed  is  ripe,  the  produce  is 

Grass,  11.8  oz.    The  produce  per  acre  125235    0  —    7827    3    0 

SO  dr.  of  grass  weigh  when  dry    36  dr.     "> 

The  produce  ofthe  space,  ditto    823  3.16>     ^^^^^  ^^  --  3522    3  12 

The  weight  lost  by  the  produce  of  one  acre  in  drying  4304  15    4 

64  dr.  of  grass  afford  of  nutritive  matter  2.3  dr.  > 

The  produce  of  the  space,  ditto  7.3  3-55  ^^^^    3—336    5    3 

The  weight  of  nutritive  matter  which  is  lost  by  taking  the 
crop  at  the  time  of  flowering,  exceeding  one  fourth  of  its 
value -        -         -       102    5  12 

The  proportional  value  in  which  the  grass  of  the 
seed  crop  exceeds  that  at  the  time  of  flowering  is  as  8 
to  11. 

The  produce  of  latter-math  is 

Grass,  7  oz.    The  produce  per  acre  76230    0  —  4764    6    0 

64  dr.  of  grass  afford  of  nutritive  matter  5  dr.      357o    4  —    223    5    4 

The  proportional  value  by  which  the  grass  ofthe 
latter-math  exceeds  that  of  the  flowering  crop,  is  as  8 
to  12,  and  that  of  the  seed  crop  as  11  to  12. 


APPENDIX.  XV. 

Here  then  is  a  satisfactory  proof  ®f  the  superior 
value  of  the  crop  at  the  time  the  seed  is  ripe,  and  of 
the  consequent  loss  sustained  by  taking  it  when  in 
flower;  the  produce  of  each  crop  being  nearly  equal. 
The  deficiency  of  hay  in  the  flowering  crop,  in  propor- 
tion to  that  of  the  seed  crop,  is  very  striking.  Its 
superior  produce,  the  highly  nutritive  powers  which 
the  grass  seems  to  possess,  and  the  season  in  which 
it  arrives  at  perfection,  are  merits  which  distinguish  it 
as  one  of  the  most  valuable  of  those  grasses,  which 
affect  moist  rich  soils,  and  sheltered  situations;  but  on 
dry  exposed  situations  it  is  altogether  inconsiderable  ; 
it  yearly  diminishes,  and  ultimately  dies  off,  not  un* 
frequently  in  the  space  of  four  or  five  years. 

XII.  Festuca  glauca.     Curtis. 

Glaucous  fescue  grass.    Nat.  of  Britain. 
At  the  time  the  seed  is  ripe  the  produce  from  a 

brown  loam  is                                               oz.  or  Ibs.  per  acre 

Grass,  14  oz.    The  produce  per  acre                152460  0  —  9528  12    0 
SO  dr.  of  grass  weigh  when  dry    32  dr.       "j 

The  produce  of  the  space,  ditto  89  21.16  3       ^°^^  0-3811    8    0 

The  weight  lost  by  the  produce  of  one  acre  in  drying  5717    4    0 
64  dr.  of  grass  afford  of  nutritive  matter  1.2  dr.  7 

rr»,         /        c.x.  Au.  ^1  1     r25r3    4—  223    5    4 

The  produce  of  the  space,  ditto  5.1  dr.  j 

At  the  time  of  flowering  the  produce  is 

Grass,  14  oz.    The  produce  per  acre                152460  0  —  9528  12  0 

80  dr.  of  grass  weigh  when  dry         32  dr.    ->  ^.^  ^       ach    «  n 

The  produce  of  the  space,  ditto         89  2  2-55  ^^^  "  ^  ^^^^    ^  " 

The  weight  lost  by  the  produce  of  one  acre  in  drying  5717    4  0 

64  dr.  of  grass  afford  of  nutritive  matter  3  dr.    >  . 

The  produce  ofthe  space,  ditto            10.2  dr.  S  9—446  10  9 

The  weight  of  nutritive  matter  which  is  lost  by  leaving  the 
crop  till  the  seed  be  ripe,  being  half  of  the  value  ofthe 

crop       .,--.,-,.  223    5    5 


XVI.  APPENDIX. 

The  proportional  value  by  which  the  grass  at  the 
time  of  flowering  exceeds  that  at  the  time  the  seed  is 
ripe,  is  as  6  to  1 2. 

The  proportional  difference  in  the  value  of  the 
flowering  and  seed  crops  of  this  grass  is  directly  the 
reverse  of  that  of  the  preceding  species,  and  affords 
another  strong  proof  of  the  value  of  the  straws  in 
grass  which  is  intended  for  hay.  The  straws  at  the 
time  of  flowering  are  of  a  very  succulent  nature;  but 
from  that  period  till  the  seed  be  perfected,  they  gradu- 
ally become  dry  and  wiry.  Nor  does  the  root  leaves 
sensibly  increase  in  number  or  in  size,  but  a  total 
suspension  of  increase  appears  in  every  part  of  the 
plant,  the  roots  and  seed  vessels  excepted.  The  straws 
of  the  Poa  trivialis  are,  on  the  contrary,  at  the  time 
of  flowering,  weak  and  tender;  but  as  they  advance 
towards  the  period  of  ripening  the  seed,  they  become 
firm  and  succulent ;  after  that  period,  however,  they 
rapidly  dry  up  and  appear  little  better  than  a  mere  dead 
substance. 

XIII.  Fcstuca  glabra.     Wither.  B.  2.  P.   154. 
Smooth  fescue  grass.     Nat.  of  Scotland. 

At  the  time  of  flowering,  the  produce  from  a  clayey 

loam,  with  manure,  is  oz.  or  Ibs.  per  acre 

Grass,  21  oz.    The  produce  per  acre  228690    0  —  14293     0     0 

80  dr.  of  ffrass  wej^^u  when  dry     32  dr.  1 

n»  /        *-*i  ^-.r   io.  ioiAo<C  91476  0—57ir    4    0 

7  he  produce  of  the  space,  ditto  134. 1  2-16  2-5  3 

The  weight  lost  by  the  produce  of  one  acre  in  drying  8576  14    0 

64  dr.  of  errass  afford  of  nutritive  matter  2  dr.     7 

r,^u  1  r.u  A'^.  inn  A    fn46    0—    446  10    0 

The  produce  of  the  space,  ditto  10.2  dr.  3 

At  the  time  the  seed  is  ripe  the  produce  is 

Grass,  14  02.    The  produce  per  acre  152460    0  —  9528  12    0 

80  dr.  of  grass  weigh  when  dry         32  dr. 
The  produce  of  the  space,  ditto       89.2  2-5 


?    60984    0  —  3811    8    0 


APPENDIX.  XVII 

oz.        or  lbs.  per  acre 
I'he  weight  lost  by  the  produce  of  one  acre  in  drying  57X7    4    0 

64  dp.  of  grass  afford  of  nutritive  matter  1. 1  dr.  ^ 

The  produce  of  the  space,  ditto  4. 1 2-16  3  ^^'^'^    0—186    1    0 

The  weight  of  nutritive  matter  which  is  lost  by  leaving  the 
crop  till  the  seed  be  ripe  exceeding  half  of  its  value  260    9    0 

The  proportional  value  which  the  grass  at  the 
time  the  seed  is  ripe,  bears  to  that  of  the  crop  at  the 
time  of  flowering,  is  as  5  to  8. 
The  produce  of  latter-math  is 

Grass,  9  02.    The  produce  per  aci;  98010    0  —  6125  10    0 

64  dr.  of  grass  afford  of  nutritive  matter  2  gr,     "i 

The  produce  of  the  space,  ditto  10  1-2  dr.5   ''^^  ^^  "~     ^7  13    0 

The  proportional  value  which  the  grass  of  the 
latter-math  bears  to  that  of  the  crop  at  the  time  of 
flowering,  is  as  2  to  8,  and  to  that  of  the  crop,  at  the 
lime  the  seed  is  ripe,  is  as  2  to  5. 

The  general  appearance  of  this  grass  is  very  simi- 
lar to  that  of  the  Festuca  duriuscula:  it  is,  however, 
specifically  different,  and  inferior  in  many  respects, 
which  will  be  manifest  on  comparing  their  several  pro- 
duce with  each  other;  but  if  it  be  compared  with  some 
others,  now  under  general  cultivation,  the  result  is 
much  in  its  favour,  the  soil  which  it  affects  being  duly 
attended  to.  The  Anthoxanthum  odoratum  being  taken 
as  an  example,  it  appears,  that 

Festuca  glabra^  affords  of  nutritive  matter 

From  the  crop  at  the  time  of  flowering  446. 7  lbs.  per  acre 

At  the  time  the  seed  is  ripe,  ditto  186.  J  ^^2. 

Anthoxanthum  odoratum^ 

At  the  time  of  flowering,  ditto  122.-^ 

At  the  time  the  seed  is  ripe,  ditto         311.3 
The  weight  of  nutritive  matter,  which  is  afforded  by  the  pro- 
duce of  one  acre  of  the  Festuca  glabra  exceeding  that  of  the 
Anthoxanthum  odoratum^  in  proportion  nearly  as  6  to  9  199. 

C 


XVIII  APPENDIX. 

XIV.  Fe^tuca  rubra.     Wither.  B.  2.  P.  153. 
Purple  fescue  grass*     Nat.  of  Britain. 

At  the  time  of  flowering,  the  produce  from  a  light 

sandy  soil,  is  02.  or  Ibs   per  acre 

Grass,  15  oz.    The  produce  per  acre  163350    0—10209    6    0 

80  dr.  of  grass  weigh  when  dry  34  dr. 


A         c.u  A..  ^nnA    -     56923  12  —  3557  11    0 

The  produce  of  the  space  ditto  102  dr 

The  weiglit  lost  by  the  produce  of  one  acre  in  drying  6651  11    0 

64  dr.  of  grass  afford  of  nutritive  matter  1.2  dr. 


The  produce  of  the  space,  ditto        22  2-16  dr.  3  ^^^^    8—239    4    8 

At  the  time  the  seed  is  ripe,  the  produce  is 

Grass,  16  oz.    The  produce  per  acre  174240    0  —  10890    0 

80  dr.  of  grass  weigh  when  dry     36  dr.  > 

'  78408  0—  4900    8    0 


36  dr.  -> 

115  346  dr.    3 


The  produce  of  the  space,  ditto 

The  weight  lost  by  the  produce  of  one  acre  in  drying  5989    8    0 

64  dr.  of  grass  afford  of  nutritive  matter      2  dr,  > 

The  produce  of  the  space,  ditto  Sdr.^^'^^^    ^""    ^^^    ^    ^ 

The  weight  of  nutritive  matter  which  is  lost  by  taking  tlie 
crop  when  the  grass  is  in  flower,  being  nearly  one  third 
part  of  its  value 101    0    8 

The  proportional  value  which  the  grass,  at  the 
time  of  flowering,  bears  to  that  at  the  time  the  seed  is 
ripe,  is  as  6  to  8. 

This  species  is  smaller  in  every  respect  than  the 
preceding.  The  leaves  are  seldom  more  than  from 
three  to  four  inches  in  length  •  it  affects  a  Soil  similar 
to  that  favourable  to  the  growth  of  the  Festuca  ovinuy 
for  which  it  would  be  a  profitable  substitute,  as  will 
clearly  appear  on  a  comparison  of  their  produce  with 
each  other. 

The  produce  of  latter-math  is 

Grass,  5  oz.    The  produce  per  acre  54450    0  —  3403    2    0 

54dr.  of  grass  afford  of  nutritive  matter  1.2  dr.     1276    2—     79  12    0 


APPENDIX.  XIX 

The  proportional  value  which  the  grass  of  the 
latter-math  bears  to  that  at  the  time  the  seed  is  ripe  is 
as  6  to  8,  and  is  of  equal  value  with  the  grass  at  the 
time  of  flowering. 

XV.  Festuca  ovina.    Engl.   Bot.  585.    Wither.  B.  2. 
P.  152.    Sheep's  fescue  grass.     Nat.  of  Britain. 

At  the  time  the  seed  is  ripe,  the  produce  is 

oz.        orlbs.  per  acre 
Grass,  8  oz.     The  produce  per  acre  87120    0  —  5445    0    0 

64  dr.  of  glass  afford  of  nutritive  matter  1.2  dr.  7 

The  pr-duce  of  the  space,  ditto  3  dr.    $203114—    1S7    9    0 

The  produce  of  latter-math  is 

Grass,  5  oz.     The  produce  per  acre  54450    0  —  3403    2    0 

64  dr.  of  g^rass  nfford  of  nutfiiive  matter  1. 1  dr.  1063    7  —      66    7    7 

The  dry  weight  of  this  species  was  not  ascertained, 
because  the  smallness  of  the  produce  renders  it  entire* 
ly  unfit  for  hay.  If  the  nutritive  powers  of  this  species 
be  compared  with  those,  of  the  preceeding,  the  in- 
feriority will  appear  thus : 

Festtiea  ovina,  (as  above)  affords  of  nutritive  matter   1.2  > 

l.li  2.2 


LI 


Ditto  ditto 

Testuca  rubra     ditto         ditto  2 

ditto  ditto         ditto 

The  comparative  degree  of  nourishment  which 
the  grass  of  the  Festuca  rubra  affords,  exceeds  there- 
fore that  afforded  by  the  F,  ovina^  in  proportion  as  1 1 
to  14. 

From  the  trial  that  is  here  detailed,  it  does  not  seem 
to  possess  the  nutritive  powers  generally  ascribed  to  it; 
it  has  the  advantage  of  a  fine  foliage,  and  may,  there- 
fore, very  probably  be  better  adapted  to  the  masticat- 
ing organs  of  sheep,  than  the  larger  grasses,  whose 
nutritive  powers  are  shewn  to  be  greater:  hence  on 
situations  where  it  naturally  grows,  and  as  pasture  for 


XX  APPENDIX. 

sheep,  it  may  be  inferior  to  few  others.     It  possesses 
natural  characters  very  distinct  from  F,  rubra. 

XVI.  Briza  media,  Engl.  Bot.  S40.  Host.  G.  A. 
2.  t.  29.  Common  quaking-grass.  "Nat.  of 
Britain. 

At  the  time  of  flowering,  the  produce  from  a  rich 

brown  loam,  is  oz.  or  Ibs.  per  acre 

Grass,  14  oz.     The  produce  per  acre  152460    0  -—  9528  12    0 

80  dr.  of  grass  weigh  when  dry    26  dr. 


!^   6551    0  —    409    7    0 


The  produce  of  the  space,  ditto  72.  3  1-16  i      ^^^^'^    ^  ""  ^^^^  ^^    ^ 
The  weight  lost  by  the  produce  of  one  acre  in  drying  6431  14    8 

64  dr.  of  grass  afford  of  nutritive  matter  2.3  dr." 
The  produce  of  the  space  ditto  9.2  2'16^ 

At  the  time  the  seed  is  ripe,  the  produce  is 

Grass,  14  oz.    The  produce  per  acre  152460    0  --    9528  12    0 

80  dr.  of  grass  weigh  when  dry    28  dr.     \       ^„ 

The  produce  of  the  space,  ditto     78. 1  :^-5  J      ^^^^^    ^  ""  ^^^^    ^    ^ 

The  weight  lost  by  the  produce  of  one  acre  in  drying         —  6183  11    0 

64  dr.  of  gi*ass  afford  of  nutritive  matter  3.1  dr. ") 

The  produce  ofthe  space,  ditto  11.  11.2  V ''^^    1—483  14 

The  weight  of  nutritive  matter  which  is  lost  by  taking  the 
crop  at  the  time  of  flowering,  being  nearly  one-fourth 
part  of  its  value 109    1    0 

The  proportional  value  which  the  grass  at  the 
time  of  flowering,  bears  to  that  at  the  time  the  seed  is 
ripe,  is  as  11  to  IS. 

The  latter-math  produce  is 

Grass,  12  oz.    The  produce  per  acre  130680    0  —  8167    8    0 

64  dr.  oF  Grass  afford  of  nutritive  matter  2  dr.      4083  12  —   255  3    12 

The  proportional  value  in  which  the  grass  at  the 
time  of  flowering,  exceeds  that  of  the  latter-math 
is  as  8  to  11;  and  the  latter-math  stands  to  that  at  the 
time  the  seed  is  ripe  in  proportion  as  8  to  13. 

•  The  merits  of  this  grass  seem  to  demand  notice ; 
jt^  nutritive  powers  are  considerable,  and  its  produce 


APPENDIX.  XXI 

large  when  compared  with  others  which  affect  a  similar 

soil. 

XVII.  Daciylis  glomerata.     Engl.  Bot.  ^^^S.     Fl. 

Dan.  743.     Round-headed  cock's-foot  grass, 
Nat  of  Britain.     Wither.  B.  2.  E.  149. 
At  the  time  of  flowering,  the  produce  from  a  rich 

sandy  loam,  is  oz.  or  lbs.  per  acre 

Grass,  41  oz.    The  produce  per  acre  ^  446490    0  —  27905  10    0 

80  dr.  of  ffrass  weich  when  dry    34  dr.  -^ 

Ti,  1  r.,  r/    o-ro.*^^       f  189758     0  —  11859  14    4 

1  he  produce  of  the  space,  ditto   278  4-5  dr.    3 

The  weight  lost  by  the  produce  of  one  acre  in  drying  16045  11  12 

64  dr.  of  grass  afford  of  nutritive  matter  2.2  dr.") 

The  produce  ofthe  space,  ditto  25.2  1-23^'^'^^^    0  —  1089   0 

At  the  time  the  seed  is  ripe  the  produce  is 

Grass,  39  oz.    The  produce  per  acre  424710    0  —  26544    6    0 

80  dr.  of  grass  weigh  when  dry  40  dr.") 

The  produce  of  the  space,  ditto       312  dr.  5  ^^^^^^^    0  —  13272    3    0 

The  weightiest  by  the  produce  of  one  acre  in  drying  13272    3    0 

64  dr.  of  grass  afford  of  nutritive  matter  3.  2  dr.^ 

The  produce  of  the  space,  ditto  34. 0  1-2  3  ^^^^^    ^  ""  ^^^^  ^^    ^ 

The  weight  of  nutritive  matter  which  is  gained  by  leaving 
the  crop  till  the  seed  be  ripe,  being  more  than  one  third 
part  of  its  value,  is 362  10    5 

The  proportional  value  which  the  grass  at  the 
time  of  flowering,  bears  to  that  at  the  time  the  seed  is 
ripe,  is  as  5  to  7,  nearly. 

The  produce  of  latter-math  is 

Grass,  17  oz.  8  dr.    The  produce  per  acre       190575    0  — •  11910  15    0 
64dr.ofgrassaffbrd  of  nutritive  matter  1.2  dr.  4466    9  —     28110    9 

The  proportional  value  which  the  grass  of  the. 
latter-math  bears  to  that  at  the  time  of  flowering,  is  as 
6  to  10;  and  to  that  at  the  time  the  seed  is  ripe,  as  6 
to  14.  64  dr.  of  the  straws  at  the  time  of  flowering 
afford  of  nutritive  matter  1 .2  dr.  The  leaves  or  latter- 
math,  and  the  straws  simply,  are  therefore  of  equgil 


xxii  APPENDIX. 

\ 
proportional  value;  a  circumstance   which  will  point 

out  this  grass  to  be  more  valuable  for  permanent  pas- 
ture than  for  hay.  The  above  details  prove,  that  a 
loss  of  nearly  one  third  of  the  value  of  the  crop  is  sus- 
tained, if  it  is  left  till  the  period  when  the  seed  is  ripe, 
though  the  proportional  value  of  the  grass  at  that  time 
is  greater,  /.  e.  as  7  ta5.  The  produce  does  not  in- 
crease if  the  grass  is  left  growing  after  the  period  of 
flowering,  but  uniformly  decreases ;  and  the  loss  of 
latter-math,  which,  (from  the  rapid  growth  of  the 
foliage  after  the  grass  is  cropped)  is  very  considerable. 
These  circumstances  point  out  the  necessity  of  keep- 
ing this  grass  closely  cropped,  either  with  the  scythe 
or  cattle,  to  reap  the  full  benefit  of  its  great  merits. 

XVIII.  Bromus  tectorum.     Host.  G.  A.  1.  t.  15. 
Nodding  pannicled  brome-grass.      Nat.    of 
Europe.     Introduced  1776.    H.  K.   1.   168. 

At  the  time  of  flowering,  the  produce  from  a 

light  sandy  soil,  is  oz.  or  lbs.  per  acre 

Grass,  11  oz.    The  produce  per  acre  119790    0  —  7486  14    0 

80  dr.  of  grass  weiffh  when  dry      42  dr.     7        ^„,,«„  -^       ^^^^    „  ,^ 
„,,  ,  r.^,*^  .'      ooi"«C       62889  12 -- 3930    9  12 

1  lie  produce  of  the  space,  do         92. 1  o-S^ 

The  weight  lost  by  the  produce  of  one  acre  in  dryino;  3556    4    4 

64  dr.  of  grass  afford  of  nutritive  matter  3     dr.  ^ 

The  produce  of  the  space,  ditto  8. 1  dr.  $  ^^^^  ^""    ^^^  ^^    ^ 

This  species  being  strictly  annual,  affords  no 
latter-math,  which  renders  it  comparatively  of  little 
value. 

XIX.  Festuca  camhrica.    Hudson.     W.  B.  2.  P.  155. 

Nat.  of  Britain. 
At  the  time  of  flowering,  the  produce  from  a  light 
sandy  soil  is 

Grass,  10  oz.    The  produce  per  acre  108900    0  —    6806    4    0 

80  dr.  of  grass  weigh  when  dry  34  dr.  ^ 

The  produce  of  the  space,  ditto  68  dr.  \  ^^^^^    ^  ~  ^892  10    8 


APPENDIX.  xxm 

oz.  or  lbs.  per  acre 

The  wfeight  lost  by  the  produce  of  one  acre  in  drying  3913    9    8 

64  dr.  of  pcrass  afford  of  nutritive  matter  2.1  dr.  7 

rru         J  r.v  J-**  irc>ioC3828    8—239    4    8 

The  produce  of  the  space,  ditto  5.2  1-2  J 

This  species  is  nearly  allied  to  the  Festuca  ovina^ 
from  which  it  differs  little,  except  that  it  is  larger  in 
every  respect.  The  produce,  and  the  nutritive  matter 
which  it  affords,  will  be  found  superior  to  those  given 
by  the  F.  ovina^  if  they  are  brought  into  comparison. 
XX.  Brotnus  Diandrus.  Curt.  Lond.  Engl.  Bot.  1006. 

Nat.  of  Britain. 

At  the  time  the  grass  is  ripe  flower,   the  produce 
from  a  rich  brown  loam,  is 

Grass,  30  oz.    The  produce  per  acre  326700    0—20418  12    0 

80  dr.  of  grass  weigh  when  dry  34  dr. 


The  produce  ofthe  space,  ditto       204  dr.  ^    ^^^^^^    8-8677  15    0 


The  weight  lost  by  the  produce  of  one  acre  in  drying  11740  13    0 

64  dr.  of  grass  afford  of  nutritive  matter  3  dr.  7 

The  produce  ofthe  space,  ditto  22.2     V^^U    1  —    957    2    1 

This  species,  like  the  preceding,  is  strictly  annual; 
the  above  is  therefore  the  produce  for  one  year,  which, 
if  compared  with  that  of  the  least  productive  of  the 
perennial  grasses,  will  be  found  inferior,  and  it  must 
consequently  be  regarded  as  unworthy  of  culture. 

XXL  Poa  angustifolia.     With.  2.  P.  142. 

Narrow-leaved  meadow  grass.     Nat,  of  Britain. 

At  the  time  of  flowering,'the  produce  from  a  brown 
loam,  is 

Grass,  27  oz.    The  produce  per  acre  294030    0  —  18376  14    0 

80  dr.  of  grass  weigh  when  dry         34  dr.     ^ 
Theproduce«fthesp.ce.ditto        183  2  Z-sj  ^^^^^^  ^2  -  7810    2  12 

The  weight  lost  by  the  produce  of  one  acre  in  drying  10566  11    4 

64  dr.  of  grass  afford  of  nutritive  matter  5  dr.  7 

The  produce  ofthe  space,  ditto  33-3    $  22886  11  -  1430    6  11 


XXIV  '  APPENDIX. 

At  the  time  the  seed  Is  ripe,  the  produce  is 

Grass,  14  oz.     ihe  produce  per  acre  152460    0  —  9528  12    0 

80  dr.  of  grass  weigh  when  dry  32  dr. 


The  produce  of  the  space,  ditto         89.2  2-5  ^y  ^^^^^    ^"~    ^^^^    ^    ^ 
The  wcig-ht  lost  by  the  produce  of  one  acre  in  drying  5717    4    0 

64  dr.  of  grass  aUbrd  of  nutritive  matter  5.  1  dr.  ^  ^ 

The  produce  of  tlie  space,  ditto            18. 1  1-2  S  ^^^^^    7  —  701    6 
The  weiglit  of  nutritive  matter  which  is  lost  by  leaving  tlie 
crop  till  the  seed  be  ripe,  exceeding  one  third  part  of  its 
value 649    0    4 

In  the  early  growth  of  the  leaves  of  this  species 
of  Pca^  there  is  a  striking  proof  that  early  flowering 
in  grasses  is  not  always  connected  with  the  most  abun- 
dant early  produce  of  leaves.  In  this  respect  all  the 
species  which  have  already  come  under  examination, 
are  greatly  inferior  to  that  now  spoken  of.  Before  the 
middle  of  April  the  leaves  attain  to  the  length  of  more 
than  twelve  inches,  and  are  soft  and  succulent;  in 
May,  however,  when  the  flower-stalks  make  their  ap- 
pearance, it  is  subject  to  the  disease  termed  rust, 
which  affects  the  whole  plant;  the  consequence  of 
which  is  manifest  in  the  great  deficiency  of  produce 
in  the  crop  at  the  time  the  seed  is  ripe,  being  one-half 
less  than  at  the  time  of  the  flowering  of  the  grass. 
Though  this  disease  begins  in  the  straws,  the  leaves 
suffer  most  from  its  effects,  being  at  the  time  the  seed 
is  ripe  completely  dried  up;  the  straws  therefore, 
constitute  the  principal  part  of  the  crop  for  mowing, 
and  they  contain  more  nutritive  matter  in  proportion 
than  the  leaves.  This  grass  is  evidently  most  valua- 
ble for  permanent  pasture,  for  which,  in  consequence 
of  its  superior,  rapid,  and  early  growth,  and  the  disease 
beginning  at  the  straws,  nature  seems  to  have  de- 
signed it.     The  grasses  which  approach  nearest  to  this 


APPENDIX.  xxt 

in  respect  of  early  produce  of  leaves,   are  the  Poa 

fertilise  Dactylis  glomerata^  Fhleum  pratense^  Alopecurus 
pratensisy    Avena  eliator,    and    Bromus   littoreus,  all 
grasses  of  a  coarser  kind. 
XXII.  Avena  eliator.     Curtis  191.    Engl.  Bot.  818. 

Holcus  avenaceus.     Tall  oat-grass.     Nat.  of 

Britain. 

At  the  time  the  seed  is  ripe,  the  produce  is 

(12.        or  lbs.  per  acre 
Grass,  24  oz.    The  pro  luce  per  acre  261360    0  — 16335  0    0 

80  dr.  of  ff rass  weigh  when  dry      28  dr.        7 

/       r.i  vJ    lo.  io^      k    91475  14  —  5717  3    14 

The  produce  of  the  space,  ditto   134. 1  3-5     J 

The  weight  lost  by  the  produce  of  one  acre  in  drying  10617  12    2 

64  dr.  of  grass  afford  of  nutritive  matter  1  dr.  7 

^.  ,         r.i  A-^,  «  i„  S    4083    12  —  255    3  12 

The  produce  of  the  sp^ce,  ditto  6  dr.  J 

The  produce  of  latter-math  is 

Grass,  20  oz.    The  produce  per  acre  217800    0  —  13612    8    0 

64  dr.  of  Grass  afford  of  nutritive  matter  1. 1  dr.    4253  14  —   265  13  14 
The  weight  of  nutritive  matter,  which  is  afforded  by  the 
crop  of  the  latter-math,  exceeding  that  afforded  by  the 
grass  of  the  seed  crop  in  proportion  nearly  as  26  to  25  10    9    2 

This  grass  sends  forth  flower  straws  during  the 
whole  season;  the  latter-math  contains  nearly  an  equal 
number  with  the  flowering  crop.  It  is  subject  to  the 
rust,  but  the  disease  does  not  make  its  appearance  till 
after  the  period  of  flowering;  it  affects  the  whole  plant, 
and  at  the  time  the  seed  is  ripe  the  leaves  and  straws 
are  withered  and  dry.  This  accounts  for  the  superior 
value  of  the  latter-math  over  the  seed  crop,  and  points 
out  the  propriety  of  taking  the  crop  when  the  grass  is 
in  flower. 

d 


XXVI  APPENDIX. 

XXIII.  Poa  eliator.     Curtis,  50. 

Tall  meadow  grass.     Nat.  of  Scotland. 
At  the  time  of  flowering,  the  produce  from  a  rich 

clayey  loam  is  oz,  or  lbs.  per  acre 

Glass,  18  oz.    The  produce  per  acre  196020    0  —  12251    4    0 

80  dr.  of  grass  weigh  when  dry    28  dr. 


The  produce  of  the  space,  ditto  100.  3  2-10  3      ^^^^^    ^  ""  ^^^^  ^^    ^ 

64  dr.  of  grass  afford  of  nutritive  matter  3.2  dr.")  ««     i«  i'> 

The  produce  of  the  space,  ditto  15.3    S  ^^"^^  13—669  15  lo 

The  weight  lost  hy  the  produce  of  one  acre  in  drying  3617  15    5 

The  botanical  characters  of  this  grass  are  almost 
the  same  as  those  of  the  Avena  eliator^  differing  in  the 
want  of  the  awns  only.  It  has  the  essential  character 
of  the  Kolci  (Florets  male,  and  hermaphrodite.  Calyx 
husks  two-valved  with  two  florets)  and  since  the 
Avena  eliator  is  now  referred  to  that  genus  this  may 
yrith  certainty  be  considered  a  variety  of  it. 
XXIV.  Festuca  duriuscula.  Engl.  Bot.  470.  W.  B. 
2.  P.  153.  Hard  fescue  grass.  Nat.  of 
Britain. 

At  the  time  of  flowering,  the  produce  from  a  light 
sandy  loam  is 

Grass,  27  oz.    The  produce  per  acre  294030    0  —  18376  14    0 

80  dr.  of  grass  weigh  when  dry       36  dr.    7  ^  ^^     «     « 

-ri  r        f.i  a;.      in^  1  q  «C  132313    8—    8269    9    0 

The  produce  of  the  space,  ditto    194. 1  3-5  J 

The  weight  lost  by  the  produce  of  one  acre  in  drying  10106    4    8 

64  dr.  of  grass  afford  of  nutritive  matter  3.2  dr.  "> 

The  produce  of  the  space,  ditto  23.2 1-23  ^^^^^  ^^ "  ^^°^  ^^  ^ 

At  the  time  the  seed  is  ripe  the  produce  is 

Grass,  28  oz.    The  produce  per  acre  304920    0  — 19075    8    0 

80  dr.  of  grass  weigh  when  dry  36  dr.  a 

The  produce  ofthe  space,  ditto    201.2  2-53   ^^^^^^    0  —  8d75  14    0 

'I'he  weight  lost  by  the  produce  of  one  acre  in  drying  10481  10    0 

64  dr.  of  grass  niford  of  nutritive  matter  1. 2  dr 

The  produce  of  tjie  space,  ditto  10. 2 


^^\    7146   9-446  10    9 


APPENDIX.  xxvn 

02.         OP  lbs.  per  acre 
The  weight  of  nutritive  matter  which  is  lost  by  leaving  the 

crop  till  the  seed  be  ripe  exceeding  one  half  of  its  value       558    5    3 

The  proportional  value  which  the  grass  at  the 
time  the  seed  is  ripe,  bears  to  that  at  the  tijne  of  flower- 
ing, is  as  6  to  14,  nearly. 

The  produce  of  latter-math  is 

Grass,  15  oz.    The  produce  per  acre  163350    0  —  10209    6    0 

64  dr.ofgrass  afford  of  nutritive  matter  1.1  dr.  3190    4 —     199    6    4 

The  proportional  value  which  the  grass  of  the 
latter-math  bears  to  that  at  the  time  of  lowering,  is  as 
5  to  14,  and  to  that  at  the  time  the  seed  is  ripe,  5  to  6. 

The  above  particulars  will  confirm  the  favourabJe 
opinion  which  was  given  of  this  grass  when  speaking 
of  the  Fesiuca  hordiformis^  and  F,  glabra.  Its  produce 
in  the  spring  is  not  very  great,  but  of  the  finest  ((quali- 
ty^ and  at  the  time  of  flowering  is  considerable.  If  it 
be  compared  with  those  affecting  similar  soils  such  as 
Foa  pratensisy  Fesiuca  ovina^  '<3'c,  either  considered  as 
a  grass  for  hay,  or  permanent  pasture,  it  will  be  found 
of  greater  value. 

XXV.  Brojnus  erectiis.  Engl.  Bot.  471.  Host.  G.  A. 
Upright  perennial  brome  grass.  Nat.  of  Bri- 
tain. 

At  the  time  of  flowering,  the  produce  from  a  rich 
sandj  soil  is 

Grass,  19  oz.    The  produce  per  acre  206910    0  —  1293114    0 

80  dr.  of  grass  weigh  when  dry     36  dr.     -j 

The  produce  of  the  space,  do       136.3  1-55         93109  8  —  5819    5    8 

The  weight  lost  by  the  produce  of  one  acre  in  drying  7112    8    8 

64  dr.  of  grass  afford  of  nutritive  matter  2.3  dr.  ^ 

TVie  produce  of  the  space,  dirto  13. 0  1-4  S  ^^^^  ^^""  ^^^  ^^  ^^ 


%xviu  APPENDIX. 

XXVI.  Milium  effusum.  Curt.  Lon.  Engl.  Bot.  1106. 
Common  millet  grass.     Nat.  of  Britain. 
At  the  time  of  flowering,  the  produce  from  a  light 

sandy  soil  is  oz.         or  lbs.  per  acre 

Grass,  11  oz.  8  dr.    The  produce  per  acre       196020    0  —  12251    4    0 

80  dr.  of  erass  weigh  when  dry  31  dr.  1 

^u  1         f.u  VM        111  oofiC  ^5957  12  — 4747    512 

The  produce  of  the  space,  ditto      111.  2  2-0  3 

64  dr.  of  grass  afford  of  nutritive  matter  1. 3  di*. 


The  produce  of  th.  space,  ditto  7.  3  2-43  ^^^^  ^^""    ^^^  ^^  ^^ 

This  species  in  its  natural  state  seems  confined  to 
woods  as  its  place  of  growth;  but  the  trial  that  is  here 
mentioned,  confirms  the  opinion  that  it  will  grow  and 
thrive  in  open  exposed  situations.  It  is  remarkable 
for  the  lightness  of  the  produce,  in  proportion  to  its 
bulk.  It  produces  foliage  early  in  the  spring  in  con- 
siderable abundance;  but  its  nutritive  powers  appear 
comparatively  little. 

XXVII.  Festuca  pratensis.  Engl.  Bot.  1592.  C.  Lond. 
Meadow  fescue  grass.     Nat.  of  Britain. 

At  the  time  of  flowering,  the  produce  from  a  bog 
soil,  with  coal  ashes  for  manure,  is 

Grass,  20  oz.    The  produce  per  acre                217800  0—- 13612    8  0 

80  dr.  of  grass  weigh  when  dry        38  dr.7 

The  produce  ofthe  space,  ditto       152  dr. 5    ^^^^^^  8-6465  15  0 

The  weight  lost  by  the  produce  of  one  acre  in  drying  —  7146    9  0 

64  dr.  of  grass  aftbrd  of  nutritive  matter  4,2  dr.  ^ 

The  produce  ofthe  space  ditto           22.2  dr.  V^^^^  1  —    957    2  1 

At  the  time  the  seed  is  ripe,  the  produce  is 

Grass,  28  oz.    The  produce  per  acre  304920    0  —    19057    8    0 

80  dr.  of  grass  weigh  when  dry  32  dr. 


The  produce  ofthe  space  ditto       179.0  4-53^^^^^^    0  —  7623    0    0 
The  weight  lost  by  the  produce  of  one  acre  in  drying  11434    8    0 

64  dr.  of  grass  afford  of  nutritiie  matter  1.2  dr. 
The  produce  of  the  space,  ditto  10.2 

The  weight  of  nutritive  matter  which  is  lost  by  leaving  the 
crop  till  the  seed  be  ripe,  exceeding  one  half  of  its  value      510    7    8 


dr.7 

^^  >7146    9—  446  10    9 


APPENDIX.  XXIX 

The  value  of  the  grass  at  the  time  the  seed  is 
ripe,  is  to  that  of  the  grass  at  the  time  of  flowering, 
as  6  to  18. 

The  loss  which  is  sustained  by  leaving  tl\e  crop 
of  this  grass  till  the  seed  be  ripe  is  very  great.  That 
it  loses  more  of  its  weight  in  drying  at  this  stage  of 
growth,  than  at  the  time  of  flowering,  perfectly  agrees 
with  the  deficiency  of  nutritive  matter  in  the  seed  crop, 
in  proportion  to  that  in  the  flowering  crop:  the  straws 
being  succulent  in  the  former,  they  constitute  the 
greatest  part  of  the  weight;  but  in  the  latter  they  are 
comparatively  withered  and  dry,  consequently  the 
leaves  constitute  the  greatest  part  of  the  weight.  It 
may  be  observed  here,  that  there  is  a  great  difference 
between  straws  or  leaves  that  have  been  dried  after 
they  were  cut  in  a  succulent  state,  and  those  which 
are  dried  (if  I  may  so  exprees  it)  by  nature  while 
growing.  The  former  retain  all  their  nutritive  powersj 
but  the  latter,  if  completely  dry,  very  little,  if  any. 

XXVIII.  Lolium  perenne.     Engl.    Bot.    315.    Fl^. 
Dan.  747.     Perennial  rye-grass.     Nat.  of 
Britain. 

At  the  time  of  flowering,  the  produce  from  a  rich 
brown  loam,  is 

oz.        or  lbs.  per  acre 
Grass,  11  oz.  8  dr.    The  produce  pep  acre        125235    0  —  7827    3    0 

80  dr.  of  grass  weigh  when  dry  34  dr.    ^ 

The  produce  of  the  space,  ditto  78  4-10  3  ^^^^^  13  —  3322    4  13 

The  weight  lost  by  the  produce  of  one  acre  in  drying  4494  14    3 

64  dr?  of  grass  afford  of  nutritive  matter  2.2  dr.  ^ 

The  produce  of  the  space,  ditto  7.0  3-4  3  ^^^^  ^^  ""  ^^^  ^^  ^* 

At  the  time  the  seed  is  ripe,  the  produce  is 

C5ra88,  22  oz.    The  produce  per  acre  239580    0  —  14973    12    ^ 


XXX  APPENDIX. 

oz.         or  lbs.  per  acre 
8.0  dr.  of  grass  weig-li  when  dry         24  dr.     "> 
The  produce  ofthe  space,  ditto        105.2  2-53    ^^^-^^    0  —  4492    2    0 

The  weight  lost  by  the  produce  of  one  acre  in  drying  10481  10    0 

64  dr.  of  grass  afford  of  nutritive  niatter  2.3  dr.  7 

The  produce  of  the  space,  ditto  15.0  2-165^^294    7—643    6    ? 

The  weight  of  nutritive  matter  which  is  lost  by  taking  the 
crop  at  the  time  of  flowering,  nearly  one  half  its  value        337    8    8 

The  proportional  value  which  the  grass  at  the 
time  of  flowering,  bears  to  that  at  the  time  the  seed  is 
ripe,  is  as  10  to  11. 

The  produce  of  latter-math  is 

Grass,  5  oz.    The  produce  per  acre  54450    0  —  3403    2    0 

64  dr.  of  grass  afford  of  nutritive  matter  1  dr.      850  12  —      53    2    12 

The  proportional  value  which  the  grass  of  the 
latter-math  bears  to  that  at  the  time  of  flowering,  is  as 
4  to  10,  and  to  that  at  the  time  the  seed  is  ripe,  as  4 
to  U. 

XXIX.  Foa  maritma.     Engl.  Bot.   1140. 
Sea  meadow  grass.     Nat.  of  Britain. 

At  the  time  of  flowering,  the  produce  from  a  light 
brown  loam  is 

Grass,  18  oz.    The  produce  per  acre  196020    0  —  12251    4    0 

80  dr.  of  grass  weigh  when  dry  32  dr.  ) 

The  produce  of  the  space,  ditto         115. 1-5  ^^^    "  "   *^°''    °    " 
The  weight  lost  by  the  produce  of  one  acre  in  drying  7350    4    0 

2  dr.  7 

Idr.r'' 

The  produce  of  latter-math  is 

Grass,  18  oz.    The  produce  per  acre  196020    0  —  12251  4    0 

64dr.ofgrass  afford  of  nutritive  matter,  1  dr.     3062  13—       191     6  31 

The  proportional  value  which  the  grass  of  the 
latter  math,  bears  to  that  at  the  time  of  flowering,  is 
33  4  to  18, 


64  dr.  of  grass  afford  of  nutritive  matter  4.  2  dr.  ^  f. 

^^3782    0  —  861    6    ^ 


APPENDIX.  XXXI 

XXX.  Cynosurus  cristatus.     Engl.  Bot.  316.     Host. 
G.  A.  2.  t.  96.     Crested  dog's-tail  grass. 

At  the  time  of  flowering,  the  produce  from  the 
brown  loam,  with  manure,  is  oz.        or  lbs.  per  acre 

Grass,  9  oz.    The  produce  per  acre  98010    0—6125  10    0 

80  dr.  of  grass  weigh  when  dry  24  dr.") 

^  '       29403    0  — 1837  11    0 


'•} 


The  produce  of  the  space,  ditto  43 

The  weight  lost  by  the  produce  of  one  acre  in  drying  4287  15    0 

64  dr.  of  grass  aflbrd  of  nutritive  matter  4.1  dr.  ^ 

Theproduceofthe  space,  ditto  9.2  1-16  3^^°^    ^ ""    ^^^  ^^    ^ 

At  the  time  the  seed  is  ripe,  the  produce  is 

Griss  18  oz.    The  produce  per  acre  196020    0  —  12251    4    0 

80  dr.  of  grass  weigh  when  dry      32  dr.        7 

The  produce  of  the  space,  ditto     115.0  8-10  ^    ^^^^^  ^  ""  ^^°^    ^    ^ 

The  weight  lost  by  the  produce  of  one  acre  in  drying  7350  12    0 

64  dr.  of  grass  afibrd  of  nutritive  matter  2.2  dr.  -^ 

The  produce  ofthe  space,  ditto  11.1  dr.l  ^^^'^    0  —  478    9    0 

Tlie  weight  of  nutritive  matter  which  is  lost  by  taking  the 
crop  at  the  time  of  flowering,  exceeding  one  sixth  of  its 
value -        -  71  12    9 

XXXI.  Avena  pratensis    Engl.  Bot.  1204.  Fl.  Dan. 
1083.     Meadow  oat-grass.     Nat.  of  Britain. 
,  At  the  time  of  flowering,  the  produce  from  a  rich 
sandy  loam,  is 

Grass,  10  oz.    The  produce  per  acre  108900    0  —  6806    4    0 

80  dr.  of  grass  weigh  when  dry  22  dr. 


The  produce  of  the  space,  ditto            44dr.i^^^'*^  8  —  187111 

The  weight  lost  by  the  produce  of  one  acre  in  drying  4934    8    8 
64  dr.  of  grass  afford  of  nutritive  matter  2.  1  dr."> 

The  produce  of  the  space,  ditto               5.  2  1-2  j^^^^  ^  ""  ^'^    ^    ^ 

At  the  time  the  seed  is  ripe,  the  produce  is 

Grass,  14  oz.    The  produce  per  acre                 152460  0  —  9528  12  0 

80  dr.  of  grass  weigh  when  dry  24  dr.  ■> 

The  produce  of  the  space  ditto            67.0  4-53  ^^''^^  ^  ""  ^^^^  ^^  ^ 

The  weight  lost  by  the  produce  of  one  acre  in  drying  6670    2  0 

64  dr.  of  grass  afvbrd  of  nuti-itive  matter  1  dr,  ^ 

The  produce  of  the  space,  ditto              3.2    3    ^^^^  ^  "^    148  14  3 


xxxii  APPENDIX. 

^,        .  ^     ^       .  ®^'         ^^  ^^^-  per  ac;  e 

The  weight  of  nutritive  matter  which  is  lost  by  leaving  the 

crop  till  the  seed  be  ripe,  exceeding  one  third  part  of  its 

'  value        -        -        -        -  ,     .        .        .        -     i  .  90    6    0 

The  proportional  value  which  the  crops,  at  the 
time  the  seed  is  ripe,  bear  to  that  at  the  time  of  flower- 
ing, is  as  4  to  9. 

XXXIII,  Bromus  multifiorus,  Engl.  Bot.  1884.  Host. 
G.  A.  1.  t.  II.  Many  flowering  brome- 
grass.     Nat.  of  Britain. 

At  the  time  of  flowering,  the  produce  from  a  clayey 
loam,  is 

Grass,  33  oz.    The  produce  per  acre  359370 

80  dr.  of  grass  weigh  when  dry  44  dr.^ 

The  produce  of  the  space  ditto      290.0  2-53   ^^''^^^ 

The  weight  lost  by  the  produce  of  one  acre  in  drying 

64  dr.  of  grass  afford  of  nutritive  matter  5  dr.  -^ 

The  produce  of  the  space,  ditto         41. 1  dr.  5  ^^^*^^  ^^ 

This  species  is  annual,  and  no  valuable  proper- 
ties have  as  yet  been  discovered  in  the  seed.  It  is 
only  noticed  on  account  of  its  being  frequently  found 
in  poor  grass  lands,  and  sometimes  in  meadows.  It 
appears  from  the  above  particulars  to  possess  nutritive 
powers  equal  to  some  of  the  best  perennial  kinds,  if 
taken  when  in  flower;  but  if  left  till  the  seed  be  ripe 
(which,  from  its  early  growth,  is  frequently  the  case), 
the  crop  is  comparatively  of  no  value,  the  leaves  and 
straws  being  then  completely  dry. 


0- 

-  22460  10 

0 

8- 

-12353  5 

8 

loior  4 

8 

12" 

- 1754  11  12 

APPENDIX.  -xx'^iii 

XXXIII,  Festuca  loUacea.     Curt.  Lond.  Engl.  Bot. 
1821.     Spiked  fescue  grass.     Nat.  of  Bri- 
tain. 
At  the  time  of  flowering,  the  produce  from  a  brown 

rich  loam,  is  oz.  or  lbs.  per  acre 

Gr«ss,  24oz.    The  produce  per  acre  261360    0  —  16335    0    0 

80  dr.  of  grass  weigh  when  dry  35dr.">    ^,,-.^     _        wi>i/;    «    r% 

o'k  J         r.u  1  ICO  1    C    114345    0~  7146    9    0 

1  he  produce  of  the  space,  do  168  dr.  j 

The  weight  lost  by  the  produce  of  one  acre  m  drying  9188    7    0 

64  dr.  of  glass  afford  of  nutritive  matter     3  dr.  ^ 

The  produce  of  the  space,  ditto  18  dr.  {  ^^251    4  —  "t^S  11    0 

At  the  time  the  seed  is  ripe,  the  produce  is 

Grass,  16  oz.    The  produce  per  acre                 174240    0  —  10890    0  0 

80  dr.  of  gra^  weigh  when  dry  33  dr.  ^ 

The  produce  of  the  space,  ditto    1053-5  dr.  V^^*"^    ^""    '^^^^    ^  ^ 

The  weight  lost  by  the  produce  of  one  acre  in  drying              6397  14  0 

64  dr.  of  grass  aflbrd  of  nutritive  matter  3.  1  dr.  ^ 

The  protluceofthe  space,  ditto             13  dr.    5    ^^^^   2  —  553    2  0 

The  latter-math  produce  is 

Grass,  5  oz.    The  produce  per  acre                     54450    0  —  3403    2    0 
64dr.of  grass  afford  of  nutritive  matter,  1.1  dr.  1063    7—        66    7    7 
The  weight  of  nutritive  matter  whicli  is  lost  by  leaving  the 
crop  till  the  seed  be  ripe,  exceeding  one  fourth  part  of  its 
value 212  11    0 

The  proportional  value  which  the  grass,  at  the 
time  of  flowering,  bears  to  that  at  the  time  the  seed  is 
ripe,  is  as  12  to  13;  and  the  value  of  the  latter-math 
stands  in  proportion  to  that  of  the  crop  at  the  time  of 
flowering,  as  5  to  12,  and  to  that  of  the  crop  taken  at 
the  time  the  seed  is  ripe,  as  5  to  13. 

This  species  of  fescue  greatly  resembles  the  rye 
grass,  in  habit  and  place  of  growth;  it  has  excellencies 
which  make  it  greatly  superior  to  that  grass,  for  the 
purposes  of  either  hay  or  permanent  pasture.  This 
species  seems  to  improve  in  produce  in  proportion  of 

e 


XXXIV  APPENDIX. 

its  age,  which  is  directly  the  reverse   of  the  LoUum 
perenne. 

XXXIV.  Poa  cristaia.  Host.  G.  A.  2.  t.  75. — Aira 
Cristata.  Engl.  Bot.  648.  Crested  meadow 
grass.     Nat.  of  Britain. 

At  the  time  of  flowering,  the  produce  from  a  sandy 

loam,  IS  oz.         or  lbs.  per  acre 

Grass,  16  oz.    The  produce  per  acre  174240    0  —  10890    0    0 

80  dr.  of  ffrass  weicfh  when  dry  36  dr.-)     , _^^     ^    ^ 

-TK  J  f.i  v..  ncQiA^     7848    0  —  4900    8    0 

The  produce  of  the  space  ditto  115  3-16  5 

The  weight  lost  by  the  produce  of  one  acre  in  drying  5989    8    0 

64  dr.  of  grass  afford  of  nutritive  matter  2  dr.  ^ 

The  produce  of  die  space,  ditto  8  dr.  3     ^^^    0  —    340    5    0 

The  produce  of  this  species,  and  the  nutritive 
matter  that  it  affords,  are  equal  to  those  of  the  Festuca 
ovina  at  the  time  the  seed  is  ripe;  they  equally  delight 
in  dry  soils.  The  greater  bulk  of  grass  in  proportion 
to  the  weight,  with  the  comparative  coarseness  of  the 
foliage,  render  the  Poa  cristata  inferior  to  the  Festuca 
ovina. 

XXXV.  Festuca  myurus,  Engl.  Bot.  1412.  Host. 
G.  A.  2.  t.  93.  Wall  fescue  grass.  Nat. 
of  Britain. 

At  the  time  of  flowering,  the  produce  from  a  light 
sandy  soil  is 

Grass,  14  oz.    The  produce  per  acre  152460    0  —  9528  12    0 

80  dr.  of  erass  weicrh  when  dry  24  dr. 7  „-^  -^     ^ 

^  r..  A-.:  z:^  o  in  C  45738    0  —  2858  10     0 

1  he  produce  of  the  space,  ditto  67  2-10 -> 

The  weight  h  st  by  the  produce  of  one  acre  in  drying  6670    2    0 

64dr.  of  grass  afford  of  nutritive  matter  1.  2  dr. ->  ^^ 

The  produce  of  the  space,  ditto  5. 1  dr.  5 

This  species  is  strictly  annual ;  it  is  likewise  sub- 
ject to  the  rust;  and  the  above  being  its  whole  pro- 
duce for  one  year,  it  ranks  as  a  very  inferior  grass. 


APPENDIX.  XXXV 

TUTMl.  Airoflexuosa.  Engl  Bot.  1519.  Host.  Go 
A.  2.  t.  43.  Waved  mountain  hair-grass. 
Nat.  of  Britain. 

At  the  time  of  flowering,  the  produce  from  a  heath 

soil,  IS                                                                 oz.  or  lbs.  per  acre 

Grass,  12  oz.    The  produce  per  acre  130680  0—  8167    8    0 
80  dr.  of  grass  weigh  when  dry          31  dr."> 

The  produce  of  the  space,  ditto         74  2-55  ^^^^S  0-3164  14    8 

The  weight  lost  by  the  produce  of  one  acre  in  drying  5002    9    8 

64  dr.  of  grass  afford  of  nutritive  matter  1. 2  dr.-^ 

The  produce  of  the  space,  ditto  4. 2  dr.  >     ^^^^  ^^  "~  "^^^    ^  ^^ 

XXXVII.  Hordeum  bulbosum.  Hort.  Kew.  1.  P.  179. 
Bulbous  barley  grass.  Nat.  of  Italy  and 
the  Levant.  Introduced  1770,  by  Mons. 
Richard. 

At  the  time    of  flowering,   the  produce  from  a 
clayey  loam  with  manure,  is 

Grass,  35  oz.    The  produce  per  acre  381150    0  —  23821    0    0 

SO  dr.  of  grass  weigh  when  dry  93  dr.  "> 

The  produce  of  the  space,  ditto       231  drj  ^^^^^^    ^  "~   ^^^^    ^    ^ 

The  weight  lost  by  the  produce  of  one  acre  in  drying  13994    7  10 

64  dr.  of  grass  afford  of  nutritive  matter  3.2  dr. 
Tlie  produce  of  the  space,  ditto  30.2  2-4^ 

XXXVIII.  Festuca  calamaria.  Engl.  Bot.  1005. 
Reed-like  fescue  grass.     Nat.  of  Britain. 

At  the  time  of  flowering,  the  produce  from  a  clayey 
loam  is 

Grass,  80  oz.    The  produce  per  acre  871200    0—54450    0    0 

80  dr.  of  grass  weigh  when  dry  28  dr. 

The  produce  of  the  space,  ditto        448  dr. 

The  weight  lost  by  the  produce  of  one  acre  iji  drying  35392    8 

64  dr.  of  grass  afford  of  nutritive  matter  4.2  dr. 

The  produce  of  the  space,  ditto  90 


■^20844    2  —  1302  12    2 


1 

^  >  304920    0  — 19057    8    0 

■eiji 
^^  j  61256    4  —  3828    S    4 


XXXVI  APPENDIX. 

At  the  time  the  seed  is  ripe,  the  produce  is 

oz.        or  lbs.  per  acrt 
Grass,  75  oz.    The  produce  per  acre  816750    0—    51046  14    0 

80  dr.  of  grass  weigh  when  dry  19  dr.  7 

The  produce  of  the  space,  ditto  283  dr.  5  ^^^^^^   ^ "~  ^^^^^  ^^    ° 

The  weight  lost  hy  the  produce  of  one  acre  in  drying  38923    4    0 

64  dr.  of  errass  alford  of  nutritive  matter  3  dr.  7 

1  c.u  r..  cA  1    S   38285    2  —  2392  13    2 

The  produce  of  the  space,  dilta  56.1  -> 

The  weight  of  nutritive  matter  which  is  lost  by  leaving  the 

crop  till  the  seed  be  ripe,  being  nearly  one  third  part  of 

lis  vahie 1435  11    2 

The  proportional  value  which  the  grass  at  the 
time  the  seed  is  ripe,  bears  to  that  at  the  time  of  flower- 
ing, is  as    2  to  1 8. 

This  grass,  as  has  already  been  remarked,  pro- 
duces a  fine  early  foliage  in  the  spring.  The  produce 
is  very  great,  and  its  nutritive  powers  are  considerable. 
It  appears  from  the  above  particulars,  to  be  best  adapt- 
ed for  hay.  A  very  singular  disease  attacks,  and 
sometimes  nearly  destroys  the  seed  of  this  grass;  the 
cause  of  this  disease  seems  to  be  unknown;  it  is  de- 
nominated Clavus  by  some;  it  appears  by  the  seed 
swelling  to  three  times  its  usual  size  in  length  and 
thickness,  and  the  want  of  the  carcle.  Dr.  Willdenow 
describes  two  distinct  species  of  it;  1st,  the  simple 
clavus,  which  is  mealy  and  of  a  dark  colour,  without 
any  smell  or  taste;  2nd,  the  malignant  clavus,  which 
is  violet  blue,  or  blackish,  and  internally  too  has  a 
blueish  colour,  a  foetid  smell,  and  a  sharp  pungent 
taste.  Brea^  made  from  grain  affected  with  this  last 
species,  is  of  a  blueish  colour;  when  eaten  produces 
cramps  and  giddiness. 


APPENDIX.  XXXVII 

XXXIX.  Bromus  littoreus.     Host.  G.  A.  P.  7.  t.  8. 
Sea-side  brome  grass.     Nat.   of  Germany, 
grows  on  the  banks  of  the  Danube  and 
other  rivers. 

At  the  time  of  flowering,  the  produce  from  a  clayey 

loam  IS  oz.  or  lbs.  per  acre 

Grass,  61  oz.    The  produce  per  acre  664290    0  —  41518    2    0 

80  dr.  of  grass  weigh  when  dry  41  dr. 


„,,  ,         p,,  ,.,,  -^^^.^.340448  10—21278    0  10 

The  produce  of  the  space,  ditto        500  2-10  3 

The  weight  lost  by  the  produce  of  one  acre  in  drying  20540    1    6 

64  dr.  of  grass  afford  of  nutritive  matter  1.2  dr.-> 

The  produce  ofthespuce,  ditto  22.3  1-25^^^^'^    4—973    1    4 

At  the  time  the  seed  Is  ripe  the  produce  is 

Grass,  S^  oz.    The  produce  per  acre  609840    0  —  38115    0    0 

80  dr.  of  grass  weigh  when  dry        32  dr.-j 

The  produce  of  the  space,  ditto       358  l-si   243936  0  -  15246    0    0 

The  weight  lost  by  the  produce  of  one  acre  in  drying  22869    0    0 

64  dr.  of  grass  afford  of  nutritive  matter  3.2  dr."> 

The  produce  of  the  space,  ditto  196     3  ^^^^^   ^  ~  ^084    6  10 

The  weight  of  nutritive  matter  which  is  lost  by  taking  the 
crop  at  the  time  of  flowering,  exceeding  one  half  of  its 
value mi    5    5 

The  proportional  value  which  the  grass  at  the 
time  of  flowering,  bears  to  that  at  the  time  the  seed  is 
ripe,  is  as  6  to  14. 

This  species  greatly  resembles  the  preceding  in 
habit  and  manner  of  growth;  but  is  inferior  to  it  in 
value,  which  is  evident  from  the  deficiency  of  its  pro- 
duce, and  of  the  nutritive  matter  afforded  by  it,  Tha 
whole  plant  is  likewise  coarser  and  of  greater  bulk  ia 
proportion  to  its  weight.  The  seed  is  affected  with 
the  same  disease  which  desti-oys  that  of  the  former 
species. 


3^xxvni  APPENDIX. 

XL.  Festuca  eliator.     Engl.  Bot.  1593.     Host.  G.  A. 
2.  t.  79.     Tall  fescue  grass.     Nat.  of  Britain. 
At  the  time  of  flowering,  the  produce  from  a  black 

rich  loam,  is  oz.  or  Ibs.  per  acre 

Grass,  75  uz.    The  produce  per  acre  816750    0  —  51046  14    0 

80  dr.  of  grass  weigh  when  dry        28  dr.- 


63808  9  —  3988    0    9 


The  produce  ofthe  space,  ditto       420  dr. 3    ^85862    8-17866    6    8 

The  weight  lost  by  the  produce  of  one  acre  in  drying  33180    7    8 

64  dr.  of  grass  afford  of  nutritive  matter     5  dr. 
The  produce  of  the  space,  ditto  93. 3 

At  the  time  the  seed  is  ripe,  the  produce  is 

Grass,  75  oz.    The  produce  per  acre              816750  0  —  51046    4  0 

80  dr.  of  grass  weigh  when  dry          28  dr.|  ^  ^ 
The  produce  of  the  space  ditto         420  dr.  3 

The  weight  lost  by  the  produce  of  one  acre  in  drying  33180    7  8 

64  dr.  of  grass  afford  of  nutritive  matter  3  dr.") 

^.  1         r.K  A-,,r.  c«  1     C  38285    2  —  2392  13    2 

The  produce  of  the  space,  ditto  56. 1    J 

The  weight  of  nutritive  matter  which  is  lost  by  leaving  the 
crop  till  the  seed  be  ripe,  exceeding  one  third  part  of  its 
value 1595    3    7 

The  proportional  value  which  the  grass  at  the 
time  the  seed  is  ripe,  bears  to  that  at  the  time  of  flower- 
ing, is  as  12  to  20. 

The  produce  of  latter-math  is 

Grass,  23  oz.    The  produce  per  acre  250470    0  —  15654    6    0 

64  dr.  of  Grass  afford  of  nutritive  matter  4  dr.    15654    6  —     978    6    6 

The  proportional  value  which  the  grass  of  the 
latter-math  bears  to  that  of  the  crop,  is  as  16  to  20; 
and  to  that  at  the  time  the  seed  is  ripe,  as  12  to  16, 
inverse. 

This  species  of  fescue  is  closely  allied  to  the  Fes* 
tuca  pratensis,  from  which  it  differs  in  little,  except 
that  it  is  larger  in  every  respect.  The  produce  is  near- 
ly three  times  that  of  the  F.  pratensisy  and  the  nutritive 


APPENDIX.  XXXIX 

powers  of  the  grass  are  superior  in  direct  proportion, 
as  6  to  8. 

XLL  Nardus  sfricta.  Engl.  Bot.  290.    Host.  G.  A. 
2.  t.  4.     Upright  mat-grass.     Nat.  of  Britain. 
At  the  time  the  seed  is  ripe,  the  produce  is 

oz.        or  lbs,  per  acre 
Crass,  9  oz.    The  produce  per  acre  98010    0  —  6125  10    0 

80  dr.  of  grass  weiffh  when  dry  32  dr.      1 

^  39204    0  —  2450    4   0 


■A 


The  produce  of  the  space,  ditto  57  2  2- 

^he  weight  lost  by  the  produce  of  one  acre  in  drying  3675    6    0 

64  dr.  of  gi'ass  afford  of  nutritive  matter  2.1  dr. ") 

The  produce  of  the  space,  ditto  5.0  1-5  ]"  ^^^^  ^°  ""  ^        ^ 

^LII.  Trittcwn,  Sp. 
Wheat-grass. 
At  the  time  of  flowering,  the  produce  from  a  rich 
sandy  loam,  is 

Grass,  18  oz.    The  produce  per  acre  196020    0—12251    4  0 

80  dr.  of  grass  weigh  when  dry   32  dr.       7 

The  produce  ofthcspace,  ditto  115  1.5      5      ^^^    0-4900    8  0 

The  weight  lost  by  the  produce  of  one  acre  in  drying  7350  12  0 

64  dr.  of  grass  afford  of  nutritive  matter  22  dr.  > 

The  produce  ofthcspace,  ditto  11.1  dr.  5  '^^^^    0—478    9  0 

XLIII.  Festucajluitans.  Curt.  Lond.  Engl.  Bot.  1520. 
Poa  fluitans.  Floating  fescue  grass.  Nat.  of 
Britain. 

At  the  time  of  flowering,  the  produce  from  a  strong 
tenacious  clay,  is 

Grass,  20  oz.    The  produce  per  acre  217800    0  —  13612    8    0 

80  dr.  of  grass  weigh  when  dry  24  dr. 

The  produce  of  the  space,  ditto         96 

The  weight  lost  by  the  produce  of  one  acre  in  drying  9528  12    0 

64  dr.  of  grass  afford  of  nutritive  matter  1.3  dr. 

The  produce  of  the  space,  ditto  8,3  dr. 

The  above  produce  was  taken  from  grass  that 
'had  occupied  the  ground  for  four  years,  during  which 


dr.l 

,     \    65340    0  —  4083  12    0 
dr.  J 

,  ^5955    0—   372    3    7 


xi  APPENDIX. 

time  it  had  increased  every  year;  it  therefore  appears 
contrary  to  what  some  have  supposed  to  be  capable  of 
being  cultivated  in  perennial  pastures. 

XLIV.  Hokus  lanatus.     Curt.  Lond.  Fl.  Dan.  118U 
Meadow  soft  grass.     Yorkshire  grass.     Nat. 
of  Britain. 
At  the  time  of  flowering,  the  produce  from  a  strong 

clayey  loam,  is  oz.         or  Ibs.  per  acre 

Crass,  28  oz.    The  produce  per  acre  304920    0—19057    8    0 

^Q  dr.  of  grass  weigh  when  dry  26  dr.  7  ^^.     ^  ^  . 

A         ^  .1  v..        n  «.r  o  o  ^  C  106585  14  -  6661    9  14 

1  he  produce  of  the  space,  ditto      157. 2  2-5  3 

The  weightiest  by  the  produce  of  one  acre  in  drying  12395  14    2 

64  dr.  of  grass  afford  of  nutritive  matter  4  dr.  ^ 

The  produce  of  the  space,  ditto  28  dr.  5    ^^^^^    8—1191 

At  the  time  the  seed  is  ripe,  the  produce  is 

Grass,  28  oz.    The  produce  per  acre  304920    0  —  19057    8    0 

80  dr.  of  grass  weigh  when  dry  16  dr."> 

The  produce  of  the  space,  ditto        89.2  2.5  3     ^^^^^    0-3811    8    0 

The  weight  lost  by  the  produce  of  one  acre  in  drying  15246    0    0 

64  dr.  of  grass  afibrd  of  nutritive  matter  2.3  dr.  > 

The  produce  of  the  space,  ditto  19. 1  dr.  3 

The  weight  of  nutritive  matter  which  is  lost  by  leaving  the 
crop  till  the  seed  be  ripe  exceeding  one  third  part  of  its 
value 372    3    8 

The  proportional  value  which  the  grass  at  the 
time  the  seed  is  ripe,  bears  to  that  at  the  time  of  flower- 
ing, is  as  1 1  to  1 2. 
XLV.  Festuca  dumetorum.     Flo.  Dan.  700. 

Pubescent  fescue  grass.     Nat.  of  Britain. 
At  the  time  of  flowering,  the  produce  from  a  black 
sandy  loam,  is 

Grass,  16  oz.    The  produce  per  acre  174240    0  —  10890    0    0 

80  dr.  ofgrass  weigh  when  dry  ^° '^''- 1  87120    0  .-.  5445    0    0 

Thj£  produce  of  the  space,  ditto  128  dr.  J 


APPENDIX,  xli 

oz.  or  lbs.  perac^e 

The  M'eigiit  lost  by  the  produce  of  one  acre  in  drying  5445    0    0 

64  dr.  of  irrass  afford  of  nutritive  matter  1  dr.  } 

J  i-.i  TM  A  u  ("      2722    8—170    2    8 

The  produce  of  the  space,  ditto  4  dr.  3 

XLVI.  Poa  fertilis.     Host.  G.  A. 

Fertile  meadow  grass.     Nat.  of  Germany. 

At  the  time  of  flowering,  the  produce  from  a  clayey- 
loam,  is 

Grass,  22  oz.    The  produce  per  acre  239580    0—14973  12    0 

80  dr.  of  crrass  weigh  when  dry  42  dr.  1 

The  produce  of  the  space,  ditto     184  4-:>  dr.  3 

The  weight  lost  by  the  produce  of  orte  acre  in  drying  7111    8    8 

64dr.  of  grass  afford  of  nutritive  matter  4.2  dr.  > 

„,,  1  n,.  V44-  o^  -       ^  16845  7  — 1052  13    7 

1  he  produce  of  the  space,  ditto  24.3       3 

If  the  nutritive  powers  and  produce  of  this  species, 
be  compared  with  any  other  of  the  family,  or  such  as 
resemble  it  in  habit  and  the  soil  which  it  affects,  a 
superiority  will  be  found,  which  ranks  this  as  one  of 
the  most  valuable  grasses;  next  to  the  Poa  angustifoUa^ 
it  produces  the  greatest  abundance  of  early  foliage,  of 
the  best  quality,  which  fully  compensates  for  the  com- 
parative lateness  of  flowering. 

XL  VII.  Arundo  color  at  a.     Hort.  Kew.  I.  P.  174. 

Engl.  Bot.  402,  Phalaris  arundinacea. 

Striped-leaved  reed  grass.     Nat.  of  Britain, 
At  the  time  of  flowering,  the  produce  from  a  black 
sandy  loam,  is 

Grass,  40  02.    The  produce  per  acre  435600    0  —  27225    0    0 

80  dr.  of  grass  weigh  when  dry  36  dr.  "> 

The  produce  of  the  space,  ditto  288  dr.  5 '''^"^O  0-12251    4    0 

64  dr.  of  grass  afford  of  nutritive  matter  4  dr.  7 

The  produce  of  the  spacfe,  ditto  40  dr.->  ^'^^^^    0—1701    9    0 

The  strong  nutritive  powers  which  this  grass 
possesses  recommend  it  to  the  notice  of  occupiers  of 

f 


m 


-lii  APPENDIX. 

Strong  clayey  lands,  which  cannot  be  drained.  Its 
produce  is  great,  and  the  foliage  will  not  be  denomina- 
ted coarse,  if  compared  with  those  which  afford  a  pro» 
duce  equal  in  quantity. 

XLVIIL  Trifolium  pratense,     W.  Bot.  3.  P.  137. 
Broad-leaved   cultivated  clover.     Nat.  of 
Britain. 

At  the  time  the  seed  is  ripe,  the  produce  from  a 
rich  clayey  loam,  is  oz.       or  lbs.  per  acre 

Grass,  72  oz.    The  produce  per  acre  784080    0  —  49005    0    0 

SO  dr.  of  grass  weigh  when  dry        20  dr.> 

The  produce  of  the  space,  ditto       288  Ur  J    ^^^''^O  0  -  12251    0    G 

The  weight  lost  by  the  produce  of  one  acre  in  drying  3675    4    C 

64  dr.  of  grass  afibrd  of  nutritive  matter  2.2       •> 

The  produce  ofthe  space,  ditto  45  dr.  530628   2  —  1914    4    2 

If  the  weight  which  is  lost  by  the  produce  of  this 
species  of  clover,  in  drying,  be  compared  with  that  of 
many  of  the  natural  grasses,  its  inferior  value  for  the 
purpose  of  hay,  compared  to  its  value  for  green  food, 
or  pasture,  will  appear;  for  it  is  certain  that  the  diffi- 
culty of  making  good  hay  increases  in  proportion  with 
the  quantity  of  superfluous  moisture  which  the  grass 
may  contain.  Its  value  for  green  food,  or  pasture, 
may  further  be  seen  by  comparing  its  nutritive  powers^ 
with  those  manifested  by  other  plants  generally  esteem- 
ed best  for  this  purpose. 

Trifolium  pratense  (as  above)  affords  of  nutritive  mattef         2.2  dr. 

XLIX.  Trifolium  repens  (white  clover)  from  an  equal  quantity 

of  grass  2.0  dr 

L,  Ditto,  variety,  with  brown  leaves,  ditto  2.2  dr. 

The  grass  of  the  T.  pratense^  therefore,  exceeds  in 
value  that  of  the  T.  repens^  by  a  proportion,  as  8  to  lOj 


APPENDIX.  xlnz 

but  it  is  of  equal  proportional  value  with  the  brown 
variety. 

LI.  Bw^net  (Poterium  sangulsorba)  affords  of  nutritive  matter       2.2  dr. 
lAl.  Bunias  orientalise  (a  newly  introduced  plant),  ditto  2.2  dr. 

The  proportional  value  of  these  two  last,  and  of 
the  T.  pratense^  and  the  brown-leaved  variety  of  T, 
repens^  are  equal:  they  exceed  the  T.  repens^  as  8  to  10. 

The  comparative  produce  of  these  four  last  metl- 
tioned  species,  per  acre,  has  not  been  ascertained* 
LIII.  Trifolium  inacrorhi%um^ 

Long-rooted  clover.     Nat.  of  Hungary. 

At  the  time  the  seed  is  ripe,  the  produce  from  a  rich 

clayey  loam,  is  oz.         or  lbs.  per  acre 

Grass,  144  oz.    The  produce  Jier  acre         1568160    0  •-    9S010    0    0 
80  dr.  of  grass  weig^li  when  dry         34  dr.     ^ 
The  produce  of  the  space,  ditto        979  1-5   j  ^^^^^^    0-41654   4    0 

The  weight  lost  by  the  produce  of  one  acre  in  drying  56355  12    0 

64  dr.  of  grass  afford  of  nutritive  matter  23  dr.-> 

The  produce  of  the  space,  ditto  99  dr.    j  ^''^^^  14  —  4211   5  14 

The  root  of  this  species  of  clover  is  biennial;  it 
penetrates  to  a  great  depth  in  the  ground,  and  is  in 
consequence  little  affected  by  the  extremes  of  wet  or 
dry  weather.  It  requires  good  shelter,  and  a  deep 
soil.  The  produce,  when  compared  to  that  of  others 
that  are  allied  to  it  in  habit,  and  place  of  growth, 
proves  greatly  superior.  The  following  particulars, 
some  of  which  refer  to  results  stated  in  the  next  two 
pages,  will  make  this  manifest:  lbs. 

Trifolium  pratense            "J  Produces  per  acre,  Grass  49005 

L  Ditto,                      Hay  12251 

Broad  leaved  clover        J  Affords,  ditto  of  nutritive  matter  1914 

Medicago  sativa.              "J  Produces  per  acre,  Grass  70785 

Lucern.    From  a  soil       I  Ditto,                      Hay  28314 

of  the  like  nature        J  Affords  of  nutritive  ir»tter  1659 


xhv  APPENDIX. 


Jfedysarum  ombi-ychis.      ")  Produces  per  acre,  Grass  8843 

[.Ditto,  Hay  3539 

Saintfoin.  J  Affords  of  nutritive  matter  314 

The  vveig-ht  of  nutritive  matter  afforded  by  the  produce  of  the  T. 
macrorhizum,  exceeding  that  of  the  T.  pnitenset  in  proportion, 
nearly  as  7  to  15 * .         .        .  2297 

The  proportional  value  of  the  grass  of  T.  protense 
to  that  of  T.  7nacrorhizu?n^  is  10  to  11. 

The  weight  of  nutritive  matter  afiiarded  by  the  T.  macrorhizum^ 
exceeding  that  of  the  Medicago  sativa,  m  proportion  nearly  as 
13  to  33 2552 

The  proportional  value  of  the  grass  is  as  11  to  6. 

The  weight  of  nutritive  matter  which  is  afforded  by  the  produce  of 
the  T.  macrorhizum^  excecdinj^  that  of  the  Hedysarum  onobrychis 
in  proportion  nctarly  as  5  to  67         -         -        -        -         -         -      3897 

The  proportional  value  of  the  grass,  like  that  of 
the  T".  prate7ise^  is  as  11  to  10. 

The  produce  of  each  of  the  above  mentioned 
species,  was  taken  from  a  similar  soil,  and  in  the  same 
situation  the  conclusions  must  thereforebe  considered 
positive,  with  respect  to  such  soils  only.  It  is  evident 
that  more  than  twice  the  quantity  of  nutritive  mattet 
is  afforded  by  the  produce  of  one  acre  of  the  T.  ma- 
crorhizum, than  from  the  produce  of  an  equal  space 
covered  by  the  T.  pratense.  Its  short  duration  in  the 
soil  (for  if  sown  early  in  the  autumn,  on  a  rich  light 
soil,  it  is  only  an  annual  plant)  rtnders  it  fit  only  for 
green-food  or  hay;  this  in  some  jneasure  lessens  its 
value,  when  compared  with  the  T.  pratense.  It  pos- 
sesses the  essential  property  of  affording  abundance  of 
good  seed;  and  if  the  ground  be  kept  clear  of  weeds, 
it  sows  itself,  vegetates,  and  grows  rapidly,  without 
covering-in,  or  any  operation  whatever.     For  four 


APPENDIX.  xlv 

years  it  has  propagated  itself  in  this  manner,  on  the 
space  of  ground  which  it  now  occupies,  and  from  which 
this  statement  of  its  comparative  value  is  made.  The 
produce  of  lucern  in  grass,  comes  nearer  to  this  spe- 
cies in  quantity,  but  is  greatly  deficient  in  nutritive 
matter,  as  much  as  13  to  33.  The  long  continuance 
of  lucern  in  the  soil  is  therefore  the  only  merit  which 
it  possesses  above  the  two  last  mentioned  species;  and 
when  that  is  the  object  of  the  cultivator,  it  will  of  ne- 
cessity have  the  preference. 

The  value  of  the  grass  of  saintfoin  is  equal  to 
that  of  the  T.  pratense;  and  proportionally  less  than 
that  of  the  Trifglium  macrorhizum,  as  10  to  11.     The 
quantity  of  grass  is  very  small,  and  on  soils  of  the  na- 
ture above  described,  it  is  doubtless  inferior.     How- 
ever, from  the  superior  value  of  the  grass,  on  dry  hilly 
situations  or  chalky  soils,  it  may  in  such  situations 
possibly  be  their  superior  in  every  respect. 
LIV.  Medicago  Sativa.     Wither.  B.  3.  P.  643. 
Lucern.     Nat.  of  Britain. 
At  the  time  the  seed  is  ripe,  the  produce  from  a  rich 

clayey  loam,  is  oz.  or  Ibs.  per  acre 

Grass,  104  oz.    The  produce  per  acre  1132560    0  —  70r85    0    0 

80  dr.  of  ffrass  vveieh  when  dry  32  dr.  7  ♦ 

^.  1         r^K  A-^,        AA- oo«  C453024    0  —  28314    0    0 

The  produce  oi  the  space,  ditto      ooa.  2  2-5  J 

The  weiglit  lost  by  the  produce  of  one  acre  in  drying  42471     0    0 

64  dr.  of  grass  afford  of  nutritive  matter  1.2  dr.  ^ 

The  produce  of  the  spac.,  ditto  39  dr.   3  ^^^^"^^   ^-^^^^     ^    ^ 

LV.  Hedysarum  onobrychis.    Wither.  3.  P.  628. 
Saintfoin.     Nat.  of  Britain. 

At  the  time  the  seed  is  ripe,  the  product  from  a  rich 
clayey  loam,  is 

Crass,  13  oz.    The  produce  per  acre  141570    0  —  8848    2    (^ 


xlvi  APPENDIX. 

oz.       or  Ibg.  per  acre 
80  dr.  of  grass  weigh  when  dry  32  dr.      J 

The  produce  oftbe  space,  ditto        83  1^  dr.  >  ^^^^8    0  —  3539    4   0 

The  weight  lost  by  the  produce  of  one  acre  in  drying  5308  14    0 

61  dr.  of  grass  afford  of  nutritive  matter  2.2  dr. ") 

The  produce  of  the  space,  ditto  8.0  1-2  j  ^^^°    ^  ""  ^^"^  ^^    ^ 

LVL  Hordeum  pratense*  Engl.  Bot.  409.  Host.  G. 
A.  1.  t.  S3.  Meadow  barley^grass.  Nat.  of 
Britain. 

At  the  time    of  flowering,   the  produce  from  a 
brown  loam,  with  manure,  is 

Grass,  12  oz.    The  produce  per  acre  130680    0  —  8167    8    0 

80  dr.  of  gi-ass  weigh  when  dry  32  dr.")  ^ 

The  produce  of  the  space,  ditto      67. 1  dr. 3       ^^^^^    0  —  o267    0    0 

The  weight  lost  by  the  produce  of  one  acre  in  drying  4900    8    0 

64  dr.  of  grass  afford  of  nutritive  matter  3.3  dr."> 

The  produce  of  the  space,  ditto  ll.ldr..5    ^^^^    0  —    478    9    0 

LVII.  Poa  compressa.     Engl.  Be*.  365* 

Flat-stalked  meadow  grass.    Nat.  of  Britain. 
At  the  time  of  flowering,  the  produce  from  a  gravelly 
soil,  with  manure,  is 

Grass,  5  oz.    The  produce  per  acre  54450    0  —  3403    2    0 

80  dr.  of  grass  weigh  when  dry  34  dr.l 

The  produce  ofthe  space,  ditto         34  dr.  5     23141    4-1446     5    4 

The  weight  lost  by  the  produce  of  one  acre  in  drying  1956  12  12 

64  dr.  of  grass  afford  of  nutritive  matter      5  dr.l 

The  pradu<:e  of  tlie  space,  ditto  6.  1    3     ^^^^  ^^ ""  ^^^  ^^  ^^ 

The  specific  characters  of  this  species  are  much 
the  same  as  those  ofthe  Poa  fertilise  differing  in  the 
compressed  figure  of  the  straws,  and  creeping  root 
only.  If  the  produce  was  of  magnitude,  it  would  be 
one  of  the  most  valuable  grasses;  for  it  produces  foliage 
early  in  the  spring,  and  possesses  strong  nutritive 
powers. 


APPENDIX.  xlvn 

LVIIL  Poaaquaiica.  Curt.  Lond.   Engl.  Bot.   1315. 
Reed  meadow  grass.     Nat.  of  Britain. 

At  the  time  of  flowering,  the  produce  from  a  strong 

tenacious  clay,  is  oz.         or  Ibs.  per  acre 

Grass,  186  OS5.    The  produce  per  acre         2025540       —126596    4    0 

80  dr.  of  ffrass  weigh  when  dry  48  dr-l       . 

^.     ,    ,.,,       ,.^/  ___^_5-  1215324  — 75957  12  0 

The  produce  of  the  space,  ditto  1785.2  2-16  J 

The  weight  lost  by  the  produce  of  one  acre  in  drying  50638    8    0 

64  dr.  of  grass  afford  of  nutritive  matter  2.2  dr.  o 

The  produce  ofthe  space,  ditto  116.1  dr.  V^^^^    —4945    2    10 

LIX.  Air  a  aquatica.   Curt.  Lond.    Engl.  Bot.  1557- 
Water  hair  grass.     Nat.  of  Britain. 

At  the  time  of  flowering,  the  produce  from  water,  Is 

Grass,  16  oz.    The  produce  per  acre  174240    0  —  10890    0    0 

80  dr.  of  grass  weigh  when  dry  24  dr.-^ 

The  produce  of  the  space,  ditto         76.3  1-16  j  ^^^^^^    0  —  3267    0    0 

The  weight  lost  by  the  produce  of  one  acre  in  drying  7623    0    0 

64  dr.  of  grass  afford  of  nutritive  matter  2. 1  dr.  -^ 

The  produce  ofthe  space,  ditto  9  dr.    j  ^^^^  ^° "~  ^^^  13  10 

LX.  Bromus  crisiaius*  Triticum  cristatum,  H.  G. 
j^L.  2.  t.  24,  Secale  prostratum.  Jacquin.  Nat. 
of  Germany. 

At  the  ticie  of  flowering,  the  produce  from  a  clayey 
16am,  is 

Grass,  13  oz.    The  produce  per  acre                141570  0  —  0848    0  0 

80  dr.  ofgras.  weigh  when  dry            32  dr.->  ^^^^^  ^_^^^^    ^  ^ 
The  produce  ofthe  space,  ditto         83. 1  dr.  J 

The  weight  lost  by  the  produce  of  one  acre  in  drying  5308  14  0 

64  dr.  of  grass  afford  of  nutritive  matter  2.2  dr.  7  '^45  10  C 
The  produce  ofthe  space,  ditto             8.0  2-165 


:Uviii  APPENDIX. 

LXI.  Elymus  Sibirlcus.     Hort.  K.  I.  P.  176.     Cult. 
1758,  by  Mr.  P.  Millar.     Siberian  lyme  grass. 
Nat.  of  Siberia. 
At  the  time  of  flowering,  the  produce  from  a  sandy 
loam,  with  manure,  is 

oz.  or  lbs.  per  acre 

Grass,  24  oz.    The  produce  per  acre               261360  0 — 16335    0  0 
80  dr.  of  g-rissweigli  wiieu  dry    28  dr.        "^ 

The  produce  of  the  space,  ditto  134.  1  2-5  5      ^^^''^  ^  "~  ^'^^'^     ^  ^ 

The  weight  lost  by  the  produce  of  one  acre  in  drying  10617  12  0 
64  dr.  of  grass  afford  of  nutritive  matter  2.1  dr.  ^ 

Theproduceoflke  space,  ditto              13.2  d  .5  ^^^^  ^         511     7  0 

LXII.  Aira  caspitosa.    Host.  G.  A.  2.  t.  42.  Engl. 
Bot.  1557.  Turfy  hair  grass.    Nat.  of  Britain, 

At  the  time  the  seed  is  ripe,  the  produce  from  a 
strong  tenacious  clay,  is 

Grass,  15  oz.     The  produce  per  acre  163350     6  —  10209  6    0 

80  dr.  of  grass  ^eigh  when  dry  26  dr.  ^ 

The  produce  of  tl.e  space,  ditto  135  1-5  5  ^^^^^  ^^""    ^^^^  °  ^^ 

The  weight  lost  by  the  produce  of  one  acre  in  drying  6891  5    4 

64  dr.  of  grass  afford  of  nutritive  matter     2  dr.  ^ 

The  produce  of  the  space,  ditto  7.2  dr.  ^  ^^^"^  ^^  "  ^^^  ^  ^^ 

LXIII.  Hordeum  fiiurinum.  Curt.  Lond.  Engl.  Bot. 
1971.  Wall  barley  grass.  Way  Bennet. 
Nat.  of  Britain. 

At  the  time  of  flowering,  the  produce  from  a  clayey 
loam,  is 

Grass,  18  oz.    The  produce  per  acre  196020    0  —  12251    4    0 

SO  dr.  of  grass  weigh  when  dry  28  dr.  "^ 

The  produce  of  the  space,  do        100.3  1-55      ^^^^^    0 -.   4287  15    0 

The  weight  l;:st  by  the  produce  of  one  acre  in  drying  7963    5    0 

64  dr.  of  grass  aflbrd  of  nutritive  matter     3  dr.  ^ 

The  produce  of  the  space,  ditto  3.3  3-16  3  ^^^^  ^^  ""  ^^^    '^  ^^ 


APPKNDIXc  ^hx 

LXIV.  Jvena  favescens.     Curt.  Lond.     Engl.  Bot. 
952.     Yellow  oat-grass.     Nat.  of  Britain. 

At  the  time  of  flowering,  the  produce  from  a  clayey 

loam,  IS  oz.  or  lbs.  per  cie 

Gr.ss,  l2oz.    The  produce  per  acre  130680    0 --- 8l6r    8    0 

80  dr.  of  i^rass  weitch  when  dry  28  dr.7  „„     ^  .^     , 

•»h.  ^     1  f*,  r..  ^^  ,    k      45738    0—2858  10    0 

I  ne  produce  or  tlie  space,  ditlo  67.  I   J 

The  weight  lost  by  the  produce  of  one  acre  in  di  ying  5308  14    0 

64  dr.  of  gr;iss  afford  of  nutji-it  i ve  matier  3  3  dr.  7 

The  produce  of  .he  space,  ditto         11.  1  dr.  S    ^^^^    0  —    478    9    0 

At  the  time  the  seed  is  ripe,  the  produce  is 

Crass,  18  oz.     The  produce  per  acre  196020     U  —  12251     4    0 

80  d.'.  of  c•ra^s  vveierli  whsn  dry  32  dr  ^ 

i  he  piodiice  of  the  sp.tce,  ditto      llo.O  4-3  ) 

The  weiglitlo.st  by  the  produce  of  one  acre  in  ctrying-  7350  12    0 

64  dr  of  CTa;  suf}(>rd  of  nutritive  matier  2  1  dr  1 

•II  1  ^'.i  •.  m  r  1      r  6!;91     5—      430  11     5 

I  lie  produce  or  the  space,   utio  lO.  !j  1-    J 

Ti  e  weight  of  nutritive  nutter  which  is  lost  if  die  crop  be 

left  till  fhe  81  ed  be  ripe,  exct-edi  g  one-tenth  part  cf  i.s 

value -        -  47  13  H 

The  proportional  value  which  the  grass  at  the 
time  the  seed  is  ripe,  bears  to  that  at  the  time  of  flower- 
ing, is  as  9  to  15. 

The  produce  of  latter-math  is 

r.rasg,  6  oz.     The  produce  per  acre  65340    0  —  4083  12    0 

64  dr.  ot  G 'ass afford  of  nutritve  matter  1.    dr.    1276    2—     79  12    2 

The  proportional  value  which  the  grass  of  the 
latter-math,  bears  to  that  at  the  time  of  flowering,  is 
as  5  to  \5'y  and  to  that  at  the  time  the  seed  is  ripe,  as 
5  to  9. 

This  species  is  pretty  generally  cultivated  in  many- 
parts  of  this  kingdom;  and  it  appears  from  the  above 
details  to  be  a  valuable  grass,  though  inferior  to  many 
others, 

g 


iry 


'J"]    269527    8  —  16845    7    8 


L      /      ]  APPENDIX, 

LXV.  Bromus  sierilis.  Engl.    Bot.    1030.  Host.  G. 
|l*  1.  t.  16.     Barren  Brome  grass      Nat.  of 
Britain. 
At  the  time  of  flowering,  the  produce  from  a  sandy 

soil  is  cz.        or  lb.  ]i     acre. 

Grass,  44  '2.  /^  he  produce  per  acre  479160    0  —  29947    8    0 

80  dr.  ofgras  weigh  when  dry        45  dr. 

The  produce  of  the  space,  ditt  >        396 

The  weljjht  lost  by  the  produce  of  one  acre  in  drying'  13102    0    8 

64  fV,  of  g-'uss  afford  of  nutritive  matter     5  df  .1 

The  produce  of  the  space,  ditto  55  dr.  5  ^^^^^  ^^  2339  10    0 

64>'dr,  of  the  flowers  afford  of  nutritive  matter  2.2  dr. 
The  nutritive  powers  of  the  straws  and  leaves  are^ 
therefore,  more  than  twice  as  great  as  those  of  the 
flowers.  This  species,  being  strictly  annual,  is  of 
comparatively  little  value.  The  above  particulars 
shew  that  it  has  very  considerable  nutritive  powers, 
more  than  its  name  would  imply,  if  taken  at  the.  time 
of  flowerings  but  if  left  till  the  seed  be  ripe,  it  is  like 
all  other  annuals  comparatively  of  no  value. 
LXVI.  Holcus  vioIHs.  Curt.  Lond.  Wither.  B.  2.  R 
134.  Creeping  soft  grass.  Nat.  of  Britain. 
At  the  time  of  flowering,  the  produce  from  a  sandy 
soil,  is 

Grass,  50  oz.    The  produce  per  acre  544500    0  —  34l31    4    0 

80  dr.  of  ffrass  weigh  when  dry  32  dr. "} 

1  f.,  rJ         ooni     5-217800    0—13612    8    0 

1  lie  produce  oi  the  space,  ditto         o20  dr.  J 

The  weight  lost  by  the  produce  of  or.e  acre  in  drying  20418  12    0 

61  dr.  of  grass  afford  (f  nutritive  matter  4.2  dr.-^  ^ 

The  produce  nfthesp^ce,  ditto  56. 1  dr.j  ^^^^^   2—2392  13    2 

At  the  time  the  seed  is  ripe,  the  produce  is 

Grass,  31  oz.    The  produce  per  acre  337590    0  —  21099    6    0 

SO  dr.  of  grass  weigh  when  dry  32  dr.  7 

The  produce  of  the  space,  do       19S.1  3-5>    ^^^^^^    0.-8439  12    0 


APPENDIX.  ii"3f        u 

oz.        or  IBs.  per  acre 
Tlie  weiglit  lost  by  the  produce  of  one  acre  in  drying  12669  10    0 

f>4  (Ir.  otcrrass  alVortl  ot  nutritive  matier  3.2  dr.-> 

„,,  ,         r.,,  v.*  ^y,.o^f  1846115  — 115313  15 

1  he  produce  of  the  space,  ditto  27.0  2-53 

The  weight  of  nutritive  matter  which  is  lost  by  leaving  the 
crop  till  the  seed  be  ripe,  being-  nearly  one  haf  oDtJ^ 
vahie ^  "'   1238  15    3 

64  dr.  of  the  roots  sfford  of  nutritive  matter  5.2  dr. 

The  proportional  value  which  the  grass  at  the 
time  the  seed  is  ripe,  bears  to  that  at  the  time  of  flower* 
ing,  is  as  1 4  to  1 8. 

The  above  details  prove  this  grass  to  have  merits 
which,  if  compared  with  those  of  other  species,  rank 
it  with  some  of  the  best  grasses.  The  small  loss  of 
weight  which  it  sustains  in  drying  might  be  expected 
from  the  nature  of  the  substance  of  the  grass;  and  the 
loss  of  weight  at  each  period  is  equal.  The  grass 
affords  the  greatest  quantity  of  nutritive  matter  when 
in  flower,  which  makes  it  rank  as  one  of  those  best 
adapted  for  hay. 

LXVII.  Poa  feriiUs.  Var.  B.  Host.  G.  A.  The 
species.  Fertile  meadow  grass.  Variety  1. 
Nat.  of  Germany. 

At  the  time  of  flowering,  the  produce  from  a  brown 
sandy  loam,  is 

Grass,  23  oz.    The  produce  per  acre               250470    0  —  15654    6  0 

80  dr.  of  grass  weigh  when  dry  34  dr.Ti 

Theproduceortlie  space,  ditto             156  2-53^^^^^^    0^6653     8  0 

The  weight  Inst  by  the  produce  of  one  acre  in  drying             9000  14  0 

64  dr.  of  grass  afford  of  nutritive  matter     3  dr.  "> 

The  produce  ofthe  space,  ditto             17.1  dr. V^^^^  ^^""  ^'^^  ^^  ^^ 

At  the  time  the  seed  is  ripe,  the  produce  is 

Grass,  22  oz.    The  produce  per  acre  239580    0  —  14973  12    0 

80  dr.  of  grass  weigh  when  dry  44  dr.  "^ 

The  produce  ofthe  space,  ditto       193.2dr.5  ^^'^^^  ^""  ^^^^    ^    ^ 


in  APPENDIX. 

oz,       or  \hs.  per  acre 
1  l»e  uelgbt  lost  by  the  produce  of  one  acre  in  drying  6738    3    0 

64  dr.  of  grass  afTord  of  nutritive  matter  5  dr.  ^ 

rn  1  r*i  J-.*  o^oj     f   18717     3  —  1169  13     3 

The  produce  of  the  space,  ditto         27.  2  dr.  j 

The  weight  of  nutritive  matter  wh'ch  is  lost  by  taking  the 
crop  at  the  time  of  flowering,  exceeding  one  third  part 
ofitsv:aueis 436    1     3 

The  proportional  value  which  the  grass  at  the 
time  of  flowering,  bears  to  that  at  the  time  the  seed  is 
ripe,  is  as  12  to  20. 

The  produce  of  latter-math  is 

Grass  7  oz.    Iht  product  pi r  iic  e  76230    0  —  4764    6 

64  dr.  of  grass  afford  otnurrviv>  m  itter,  1.2  dr.      1786  10—  111  10  10 

The  proportional  value  which  the  grass  of  the 
latter-math,  bears  to  that  at  the  time  of  flowering,  is 
as  6  to  12j  and  to  that  at  the  time  the  seed  is  ripe,  as 
G  to  20. 

LXVIII.  Cynosurtis  erucaformis,     Beckmannia  erucse- 
formis.     Host.  G.  A.  3.  t.  6. 
Linear-spiked    dog's-tail   grass.       Nat.   of 
Germany. 
At  the  time  the  seed  is  ripe,  the  produce  is 

Grass,  18  oz.    The  produce  pci  ac  e  196020    0  —  12251    4    0 

89  dr.  of  grass  weigh  when  dry   36  dr. 


r..  r..    loooo^v      ^8209    0  —  5513    1    0 

The  priiduce  of  the  space,  ditto  129.  2  2-5  3 

1  he  weightiest  by  the  produce  of  one  acre  in  drying  6738    3    0 

64  «r  of  g.  ass  afford  of  nutritive  matter  3.1  dr.^  ^^^^    2—622    2    2 
The  produce  of  the-  .space,  ditto  14.2  2  43 

LXIX.  Phleum  nodosum.     W.  B.  2.  P.   118. 

Bulbous  stalked  cat's-tail  grass.     Nat.  of  Bri- 
tarn. 
At  the  time  of  flowering,  the  produce  from  a  clayey 
loam,  is 

Grass,  18  oz.    The  produce  per  acre  196020    0-12251    4    0 


APPENDIX.  Liii 


(DZ.  or  lbs.  per  acre 

93109    8—    5819    5     S 


€0  dr.  of  grass  weljjli  when  t!ry  38  dr. 

The  produce  of  the  Sfjact,  ditto  136  4-5 

The  weight  1  st  by  the  produce  of  one  ac'e  in  drying  6431  14    8 

64  dr.  of  c-rass  aflbrd  of  nutritive  matter  2.2  dr.  } 

1111    <7657    0—478    9    0 
1  he  pr  diice  of  tht-  sp-jc  ,  ditto  11.1  dr.  3 

This  grass  is  inferior  in  many  respects  to  the 
Phleum  pratense.  It  is  sparingly  found  in  meadows. 
From  the  number  of  bulbs  which  grow  out  of  the 
straws,  a  greater  portion  of  nutritive  matter  might 
have  been  expected.  This  seems  to  prove,  that  these 
bulbs  do  not  form  so  valuable  a  part  of  the  plant  as 
the  joints,  which  are  so  conspicuous  in  the  Phleum 
fratense^  the  nutritive  powers  of  which  exceed  those  of 
the  P,  nodosum-y  as  8  to  28. 
LXX.  Phleum  pratense.     Wither.  2.  P.  1 1  ?• 

Meadow  cat's-tail  grass.     Nat.  of  Britain. 
At  the  time  of  flowering,  the  produce  from  a  clayey 
loam,  is 

GrMs.,  60  .z.    The  produce  per  acre  653400    0  —  40837    8    0 

80  dr.  of  grass  weigh  when  dry  34  dr.-> 

The  produce  of  the  space,  ditto  408  dr.  5  ^^^^^^    ^  ""  ^''^^^  ^^    ^ 

The  weighi  lost  by  the  produce  of  one  acre  in  drying  23481    9    0 

64  dr.  of  grass  afford  of  nutritive  matter  2-2  <'r. 


The  pro<luc,  of  the  space,  ditto  37.2  dr.  ^  ^^^^^  '^  ~"  ^^^^    ^    ^ 

The  weight  of  nutritive  matter  which  is  lost  by  leaving  Uie 

crop  !ill  the  seei'  b^ripe,  excee  lingone  hnlfof  it^'-  v:.lue      2073  11    0 

At  the  time  the  seed  is  ripe,  the  produce  is 

Gra.ss,  bU  1)2.  1  he  produce  per  acre       6534UU  0  —  40337  8  0 

"■•? 

The  produce  of  the  space,  ditto  456  dr.  3 

The  weight  lost  by  Ihe  p  oduce  of  one  acre  in  drying  21439  11    0 

64  dr  of  gi'ass  afford  of  nut'"itive  m.ttter  5.3  dr.  ) 

The  produce  of  the  space,  ditto  86.1  dr.  5  ^^'^^^  14  —  3668  15  U 

The  latter-math  produce  is 

Grass,  14  02.     \  he  pn^duce  ptr  acre  152460    0  —  9528  12    0 

64dr.ofgrass  afford  of  nutritive  matter  2  dr.     4764    6—    297  12    6 


80  dr.  of  grass  weigh  when  dry  38  dr. , 

310365   0  —  19397  13    0 


Liv  APPENDIX. 

64  dr.  of  the  straws  afford  of  nutritive  matter  7  dr. 
The  nutritive  powers  of  the  straws  simply,  therefore, 
exceed  those  of  the  leaves,  in  proportion  as  28  to  8; 
and  the  grass  at  the  time  of  flowering,  to  that  at  the 
time  the  seed  is  ripe,  as  10  to  23;  and  the  latter-math, 
to  the  grass  of  the  flowering  crop  as  8  to  10. 

The  comparative  merits  of  this  grass  will  appear, 
from  the  above  particulars,  to  be  very  great;  to  which 
may  be  added  the  abundance  of  fine  foliage  that  it 
produces  early  in  the  spring.  In  this  respect  it  is 
inferior  to  the  Poafertilis,  and  Poa  anguesiifolia  only. 
The  value  of  the  straws  at  the  time  the  seed  is  ripe, 
exceeds  that  of  the  grass  at  the  time  of  flowering,  as 
28  to  10;  a  circumstance  which  increases  its  value 
above  many  others  ;  for,  by  this  property,  its  valuable 
early  foliage  may  be  cropped,  to  an  advanced  period  of 
the  season  without  injury  to  the  crop  of  hay,  which,  in. 
other  grasses  which  send  forth  their  flowering  straws 
early  in  the  season  would  cause  a  loss  of  nearly  one 
half  of  the  value  of  the  crop,  as  is  clearly  proved  by 
former  examples ;  and  this  property  of  the  straws, 
inakes  the  plant  peculiarly  valuable  for  the  purpose  of 
hay. 

LXXI.  Phleum  pratense,  Var.  minor.  Wither.  B. 
2.  118.  Var.  1.  Meadow  cat's-tail  grass. 
Var.  Smaller.     Nat  of  Britain. 

At  the  time  of  ripening  the  seed,  the  produce  from  a 

clayey  loam,  is  oz.  or  .hs  per  acre 

Grass,  40  oz.    The  produce  per  acre  435600    0  —  27225    0    0 

80  dr.  of  crrass  weigh  when  dry  34  dr  ">  ^     .„     » 

1  .-.,  r.;  o-ro  1    C  185130   0-11570  10    0 

1  he  produce  ol  the  space,  ditto  272  dr.  J 


APPENDIX.  i.v 

oz  or  lbs  pei*  acre 

The  \vel{^it  lost  by  the  produce  of  one  acre  in  drying  15654    6    0 

64  dr.  of  grass  attbrd  of  nutritive  mattei*  2.3  dr. 7  ^        i  -     i«5     >> 

The  produce  of  the  space,  ditto              272  dr.i  ^^^^^  ^  "~  ^^^^  ^^    -^ 

The  latter-math  produce  is 

Crass,  14  oz.    The  produce  per  licre  152460    0—9528  12    0 

64  dr.  of  grass  jifford  of  nutritive  matter  1  2.  dr.  3573    4  —   223     5    4 

LXXII.  ElyniKs  arenarius.     Engl.  Bot.  1672. 

Upright  sea  lyme  grass.     Nat.  of  Britain. 

At  the  time  the  seed  is  ripe,  the   produce  from  a 
clayey  loam,  is 

Grass,  64  oz.    The  produce  per  acre  696960    0  —  43560  0  0 

HO  dr.  of  grass  Wtii^ii  when  dry  45  dr."> 

The  produce  of  U>esp»c..,  ditto        570  dr.  j    392040    0-24502  8  0 

The  weight  lost  by  the  produce  of  one  acre  in  drying  1%9^'t  8  0 

64  dr.  of  grass  atlbrd  of  nutritive  matter  5  dr.  ) 

The  produce  of  the  space,  ditto  80  dr.  S     ^'^'^^^     0  —  3403  2  0 

LXXIII.  Elymus  genicidatics.  Pendulous  lyme  grass. 
Engl.  Bot.  1586.  Pendulous  sea  lyme 
grass.     Nat.  of  England. 

At  the  time  of  flowering,  the  produce  from  a  sandy 
soil,  is 

Grass,  30  oz.    The  produce  per  acre             326700  0  —  20418  12  0 

80  di\  of  grass  weigh  when  dry  32  dr.  ^ 

The  produce  of  the  space,  ditto      192  dr.  5    ^^^^^^  0—8167    8  0 

The  weight  lost  by  the  produce  of  one  acre  in  drying  12251    4  0 

64dr.of  grass affordofnutritivematterS.l dr.  ^ 

The  produce  of  the  space,  ditto   24.1  1-2  dr.  5  ^^^^°  ^  "  '^^^^  ^^  ^ 

LXXIV,  Bromus  inermis.     Host.  G,  A.  1.  t.  9. 

Awnless  brome  grass.     Nat.  of  Germany. 

Introduced  by  Mr.  Hunneman  in  1794. 
At  the  time  the  seed  is  ripe,  the  produce  from  a 
black  sandy  soil,  is 

GjKss,  18oz.    The  produce  per  acre  196020    0  —  12251    4    0 

80  dr.  of  grHss  weigh  witen  dry  25  dr.  ^ 

I  he  prodjicfe  of  Mie  s^act.  ditto        126  dr.  S    ^^^'^^  ^^  "-  ^^^^  '  ^  ^^ 


Lvi  '  APPENDIX. 

o^.        or  lbs.  ])er  acre. 
The  weig^iit  lost  by  the  produce  of  one  acre  in  drying  6891    5    4 

64  dr.  of  ;,^rass  afford  of  nutritive  matter  4.  1  dr.  7 

The  produce  of  the  space,  ditto       X9.0  3-5       ]"  ^^^^^  15—813     8  15 

The  produce  of  iatter-math  is 

Grass,  13  (;z.      I  he  vroduce  per  acu-  A41570    0—8843    2    0 

64  dr.    f  jjrassaifudor  imi.itivc  malter  1.  1  dr.   2765     0 —    172  13    0 

LXXV.  Agrostis  vulgaris.  Wither.  Bot.  2,  132. 
Hud.  A.  capilaris,  Dr.  Smith,  A.  arenaria. 
Fine  bent  grass.     Nat,  of  Britain. 

At  the  time  the  seed  is  ripe,  the  produce  from  a 
sandy  soil,  is 

Grass,  14  uz.    The  produce  per  acre  152460    0—9528  12    0 

80  dr.  of  crrass  weie:h  when  dry  40  dr  ") 

.,,,  ,  -..,  ,.'  ,,,        f    76230    0  —  4764    6    0 

I  he  produce  ot  the  space,  ditto  112  (ir.J 

The  weight  lost  by  tlie  produce  of  one  j.cr-  in  drying  476  i    6     0 

64  dr.  of  grass  afford  of  nutritive  matter  1.2  3-16  dr.  > 

The  produce  ofthe  space,  ditto  5.11-16      54019  15  —  2513  15 

This  is  one  of  the  most  common  of  the  bents, 
likewise  the  earliest  \  in  these  respects  it  is  superior 
to  all  others  of  the  same  family,  but  inferior  to  several 
of  them  in  produce,  and  the  quantity  of  nutritive  mat- 
ter it  affords.  As  the  species  of  this  family  are 
generally  rejected  by  the  cultivator  on  account  of  the 
lateness  of  their  flowering ;  and  this  circumstance,  as 
has  already  been  observed,  does  not  always  imply  a 
proportional  lateness  of  foliage,  their  comparative 
merits  in  this  respect  may  be  better  seen,  by  bringing 
them  into  one  view,  as  to  the  value  of  their  early 
foliage. 


APPENDIX.  LYii 

The  apparent  t'lfference  of  time.     Their  nutritive  powers. 


Jo-rostis  vulgaris 

Middle  of  April 

1.2  3.4 

palustris 

One  week  later , 

2.3 

stolonifera     TvVo,  ditto        • 

3.2 

canina 

Ditto,  ditto 

1.3 

stricta 

Ditto,  ditto 

1.2 

nivea 

Three  weeks,  ditto 

2 

littoralis 

Ditto,               ditto 

3 

repens 

Ditto,               ditto 

3 

mexicana 

Ditto,               ditto 

2 

fascicularis  Ditto,                ditto 

2 

LXXVI.  Agrostis 

palustris.    Wither.  Bot.  2,  P.  129, 

Var.  2,  ; 

alba.  Engl.  Bot.  1189. 

A.    alba. 

Marsh  bent  grass. 

At  the  time  of  flowering,  the  produce 

from  a  bog 

earth,  is 

oz. 

or  lbs.  per  acre 

Grass,  15  oz.     The  prod 

uce  per  acre        163350 

6  —  10209    6    0 

80  dr.  of  grass  weigh  when  dry  36  dr."^ 

Theproduceofthe  space,  ditto  ISOdr.  V^^^'^      8  —  4594    3    8 

The  weight  lost  by  the  produce  of  one  acre  in  drying  5615    2    8 

64  dr.  of  grass  afford  of  nutritive  matter  2. 3  dr.") 

The  produce  of  the  space,  ditto  lO.1 1-43  ^^^^  ^^"^  ^^^     ^^  ^^ 

At  the  time  the  seed  is  ripe,  the  produce  is 

Grass,  20  oz.    The  produce  per  acre  217800    0  —  13612    8    0 

80  dr.  of  grass  weigh  when  dry  32  dr.  "Ji 

The  produce  of  the  space,  ditto  128  dr.  j 

The  weight  lost  by  the  produce  of  one  acre  in  drying 


87120  0  — 

5445    0    0 

Irying 

8167    8    0 

j  9358  9  — 

584    14  9 

64  dr.  of  grass  afford  of  nutritive  matter  2.3  dr. 
The  produce  of  the  space,  ditto  13.3  dr- 

The  weight  of  nutritive  matter  which   is  lost  by  taking  the 
crop  at  the  time  of  flowering,  being  one  fourth  part  of  its 

value -        -  146    3     1\> 

The  proportional  value  of  grass,  in  each  crop  is  equal. 

h 


Lviii  APPENDIX. 

LXXVIL  Fanicum  dactylon.  Engl.  Bot.  850.  Host. 
G.  A,  2,  t.  18.  Creeping  Panic  grass, 
Nat.  of  Britain. 

At  the  time  of  flowering,  the  produce  from  a  sandy 
loam,  with  manure  is 

oz         or  lbs  per  acre 
Grass,  46  oz.    The  produce  per  acre  500940    0— 31308  12    0 

80  dr.  of  grass  weigh  when  dry  36  dr."> 

The  pioduce  of  the  space,  ditto        S31.0  4-55  ^25423    0 - 14088  15    0 

The  v/eight  lost  by  the  produce  of  one  acre  in  drying"  17219    13  0 

64  dr.  of  grass  afford  of  nutritive  matter    2.  dr.  1 

The  pro  'uce  of  the  space,  ditto  23.  dr.J  ^^^^^  ^~  ^^^^^   ^  ^ 

LXXVIII.  Jgrostis  siolonifera.     Engl.  Bot.  1532. 

Wither.  Bot.  2,  181.  (Fiorin,  Dr.    Rich- 
ardson.) 
Creeping  bent.     Nat.  of  Britain. 

At  the  time  of  flowering,  the  produce  from  a  bog 
soil,  is 

Grass,  26  oz.    The  produce  per  acre  283140    0—17^96    4    0 

80  dr.  of  grass  weigh  when  dry  35  dr.  ) 

^M     ^     1         f.K  v..  iRo^.  C  127413   0-7963      5   0 

The  produce  ui  the  space,  ditto  182  dr.  j 

The  weig:.  lost  by  Ihe  produce  of  one  acre  in  drying  9732    15    0 

64  dr.  of  grass  afford  of  nut-itive  matter  3.2  dr.  ) 

^  ^  15484  3  —967    12    3 


■:\ 


The  produce  of  tht  space,  ditto  22.3  dr, 

At  the  time  the  seed  is  ripe,  the  produce  is 

Grass,  28  oz.    The  produce  per  acre  304920    0  —  19057  8    0 

80  dr.  of  grass  weigh  when  dry  ^^  ^^-1,0-01/     n      ft^-^    izi    n 

The  produce  of  thw  space,  ditto     201.2  2-5  J   ^'''^-^*    0-b5r5     li 

The  weight  lost  by  the  produce  of  one  acre  in  drying  104S1  10    0 

64  dr.  of  grass  afford  of  nutritive  matter  3.2  dr.-* 

,  c.u  A',.  CA  c,  y    {-16675  0  —  1042    3    5 

1  he  produce  ot  the  space,  ditto  24. 2  dr.3 

The  weiglit. of  nutritive  matter  whichis  lost  by  taking  the  crop 

at  the  time  of  flowering,  being  nearly  one  fourteenth  of  its 

value        .        « ri    7    2 


APPENDIX.  ux 

V 

LXXIX,     Agrostis  stolonifera.    Van     angustifolia. 
Creeping  bent  with  narrow  leaves. 
Nat.  of  Britain. 
At  the  time  the  seed  is  ripe,  the  produce  from  a 
bog  soil,  is 

oz.  OP  lbs.  per  acre 

Grass,  24  oz.    The  produce  per  acre              261360  0  —  16335    0    0 

80d^.ofg«s,wigI,^vhen^ry          36.1iv->  ^^    ^ 
The  produce  or  ihe  Space,  ditto    172  3  1-53 

The  weight  lost  by  the  produce  oi  Oi-e  Kcre  in  drying  8984    4    0 

64  dr.  of  grass  afFtird  ofnutritivt  matter  3.  dr.  > 

The  pro  luce  of  th*;  space,  ditto  18  d-  5  ^^^^^    4  —  765    11 

The  weight  of  nutritive  matter  afforded  by  the  pro- 
duce of    one  acre  of  the    Agrostis   stolo  jera, 
vexceeding  that  of  the  variety  in  proportion,  is  6 
to  8         .         -         -         .  276     8     1 

The  above  details  will  assist  the  farmer  in  deci- 
ding on  the  comparative  value  of  this  grass  From  a 
careful  examination  it  will  doubtkss  appear  to  possess 
merits  well  worthy  of  attention,  though  perhaps  not 
so  great  as  has  been  supposed,  if  the  natural  place  of 
it«  growth  and  habits  be  impartially  taken  into  the  ac- 
count. From  the  couchant  nature  of  this  grass,  it  is 
denominated  couch-grass,  by  practical  men,  and  from 
the  length  of  time  that  it  retains  the  vital  power,  after 
being  taken  out  of  the  soil,  is  called  squitch,  quick,  full 
of  life,  &c. 

LXXX.  Agrostis  canina,     Engl.  Bot.  1 S56. 
Brown  bent.    Nat.  of  Britain. 

At  the  time  of  flowering,  the  produce  from  a  brown 
sandy  loam,  is 

Grass,  9  oz.    The  produce  per  acre  98010    0  —  6125    10    0 


i^x  APPENDI?v. 

oz.         or  lbs.  per  acre. 
80  dr.  of  grass  weigh  when  dry  34  dr.  } 

The  produce  of  the  space,  ditto  63  1-5  $      ^^^^^  ^  ~  2688    5    0 

The  weight  lost  by  the  produce  of  one  acre  in  drying  34.37    5    0 

64  dr.  of  grass  afford  of  nutritive  matter  2.2  d' .  ") 
The  produce  of  the  space,  ditto         5  211-2       ]"      3823  8  —  239    4     6 

LXXXL     Agrosiis  canina.  Var.  muticae. 

Awnless  brown  bent.     Nat.  of  Britain. 
At  the  time  the  seed  is  ripe,  the   produce  from  a 
sandy  soil,  is 

Gfrss,  21oz.    The  produce  per  acre                228690  0—14293    2  0 
80  dr.  of  grass  weigh  when  dry         24  dr.  ^ 

The  produce  of  the  space,  ditto  100.3  1-5  5    ^^^^'^  0-4287     15  0 

The  welglit  lost  by  the  produce  of  one  acre  in  drying  ICOOo    3  0 

64  dr.  of  grass  afford  of  nutritive  matter  1.3  dr.  ^ 

The  prorhice  of  fht-  .<j.  ce,  ^titto  9.0  3-4  5  ^^^^   3  —  390    '13      3 

The  weight  of  nutritive  matter  which  the  produce  of 
one  acre  of  the  awnless  variety,  exceeds  that  of 
the  last  mentioned  species         -         .5       8     11 
LXXXIL     Agrosiis  stricta.     Curt.     A.  rubra. 
Upright  bent  grass.    Nat.  of  Britain. 
At  the  time  the  seed  is  ripe,  the  produce  from  a 
bog  soil,  is 

Grass,  11  oz.    The  produce  per  acre  119790    0  —  7486    14    0 

80  dr.  of  griiss  weigh  when  dfy  29  dr.  "> 

The  produce  of  the  space,  do      63  4-5  dr. 5 /^^^23    14-2713  15    0 

The  weight  lost  by  the  produce  of  ono  acre  in  drying  4772    15    0 

64  dr.  of  grass  afford  of  nutritive  matter  1-2  dr.  1 

The  pr.'duce  of  the  spacf,  ditto         4.0  5-10   5  ^^^'^     9  —  175      7    9 

LXXXIIL     Agrosiis  nivera, 

Snowey  bent  grass.     Nat.  of  Britain. 
At  the  time  the  seed  is  ripe,  the  produce  from  a 
sandy  soil,  is 

Grass,  7  oz.    The  produce  per  acre  76230    0  —  4764    6    0 


^^5      10890     0—680    10    0 


APPENDIX.  Lxi 

oz.         or  lbs.  per  acre 

50  dr.  of  ffrass  wei2:h  wben  dry        22  dr.-> 

Tu  1         r.u  1       onoic4    ^    20963    4  —  1310        3    0 

The  produce  of  the  space,  do.    30.3  1-5  dr.  5 

The  weight  lost  by  the  produce  of  one  acre  in  drying  3454    3    0 

64  dr.  of  gTfiss  afford  of  nutritive  matter    2  dr."^ 

The  nryiuc- of  the  space,  ditto  3    1-2  dr  S"      238:3—148     14    5 

LXXXIV.     Agrosiis  fascicularis,     Huds.     Var. 
canina.     Curt.     Tufted  leaved  bent. 
Nat.  of  Britain. 

At  the  time  of  flowering,  the  produce  from  a  light 
sandy  soil,  is 

Gris;,  4  >z.      The  produce  per  acre  43560     0  —  2722      8    0 

'80  dr.  oi  grass  Wfij^'h  wh.^i'  dry  20  fir." 

Tlie  produce  of  the  sp^ce,  ditto  16 . 

The  weight  lost  by  tlie  produce  of  one  acr<.  in  dying  2041     14    G 

^64  dr.  of  grass  afford  of  nutritive  matter  2  dr.  "> 
tii^'^oducenfthe  s-ace,ditt.    '       ■    2  dr;>      1S61    4  _  85       1    4 

LXXXV.     Festuca  pinnafa,     Brotntis  pinnatus. 

Engl.     Bot.     730. 

Spiked  fescue.    Nat.  of   Britain. 
At  the  time  the  seed  is  ripe,  the  produce  from  a 
light  sandy  soil,  with  manure,  is  ''■       ' 

Grass,  30  jz.      Tiie  pro.uce  per  »cie              326700  i  O  — 20418  12    0 

80  dr.  of  grass  weigh  when  dl*y  32  dr.  ?  ;  '     r : 

The  produce  of  the  sface.diuo          192  dr.  S '^°®^    ''-»^^''  «    0 

The  weight  lost  by  the  produce  of  one  acre  in  drying            12251  4    0 

64  dr.  of  j-^rass  afford  uf  nutritive  matier  1 1  (h\  )       ' 

The    -  drc.  <.fth.  sp^  ,  ditto              9  1,2-4  S  ^^^^  ^^  "  ^^^  ^^  ^^ 

LXXXVI.     Panicupi    viride.     Curt.     Lond.     EngL 
Bot.     675.  Green  panic  grass.  Nat.  of 
Britain. 
At  the  time  the  seed  is  ripe,  the  produce  from  a 

light  sandy  soil,  is 

Grass,  8  oz.    The  produce  per  acre  87120    0  —  5445    0    0 


*xu  APPENDIX. 

oz.  or  lbs  per  acre 

JlO  dr.  of  grass  weigh  when  dry   32  dr.       ")  ; 

The  produce  of  the  space,  ditto       51  1-5  3      ^^^^^    °  *~  ^^''^    ^    ^ 
The  weight  lost  by  the  produce  of  one  acre  in  drying  326r    0    • 

64  dr.  of  grass  afPrrd  of  nutritive  matter  1.2  dr.  > 
The  produce  of  ihc  .-pace,  duto  3  dr-  5  ^^^^     ^^ "~  ^^'^    ^  ^* 

LXXXVII.  Panicumsanquinale,  Curt.  Lond.  Engl. 
Bot.  849.  Blood  coloured  panic  grass. 
Nat.  ofBritain.^ 

At  the  time  the  seed  is   ripe,  the  produce  from  a 
sandy  soil,  is 

Grass,  10  oz     The  produce  per  acre  108900   0—6806  4    0 

64  dr.  of  grass    ff.rd  of  nutritive  matter  10  2-16     1914  4—    1'9  10  4 

This  and  the  preceding  species  are  strictly  annu- 
al, and  from  the  results  of  this  trial,  their  nutritive 
powers  appear  to  be  very  inconsiderable.  The  seed 
of  this  species,  Mr.  .Schreber  describes  (in  Beschrei- 
bung  der  Graser)  as  the  manna  grass.  In  Poland, 
Lithuania,  &c.  it  is  collected  in  great  abundance,  when 
after  being  thoroughly  separated  from  the  husks,  it  is 
fit  for  use.  When  boiled  with  milk,  or  wine,  it  forms 
an  extremely  palatable  food,  and  is  most  commonly 
made  use  of  whole,  in  manner  of  sago,  to  which  it  is  in 
general  preferred. 

LX XXVIII.    Agrostis  lobata.     Curtis,  lobtita  et  are- 
naria.     Lobed  bent  grass. 

At  the  time  of  flowering,  the  produce  from  a  sandy 
soil,  is 

Grass,  IC  oz.    The  produce  per  acre  108900    0  —  6806    4    0 

•«0  dr.  ofgrass  weigh  when  dry  40dr.-j    ^^^^^    o~3403    2    0 

The  produce  of  the  space,  ditto  80  dr.  5 

The  weight  lost  by  the  produce  of  one  ac^e  in  drying  3403    2    0 


APPENDIX.  Lxm 


oz.  or  lbs.  peracr* 

64dr.ofgrassaflror.lornutntive*matter  ^'^^■'?  5104  ll—ng 

Thf  produce  of  the  spuce,  ditto  7.2  dr.  ^ 

LXXXIX.     Agrostis  repens.    Wither.  Bot.  A.  nigra. 
Creeping  rooted  bent,   black  bent.  Nat. 
of  Britain. 
At  the  time  of  flowering,  the  produce  from  a  clayey 
loam,  is 

Grass,  9  oz.    The  pro  luce  per  acre  98010    0  —  6125    10    0 

.»  dr.  ofgrass  weigh  when  dry  35dr,->      ,2879  6  -  26r9    15   6 

The  produce  of  the  space,  ditto  60  cli  •  j 

The  weight  last  by  the  produce  of  one  acre  in  drying  5445    10  10 

54  dr.  of  grass  afford  of  nutritive  matter    odr.  "> 

The  pr,jduce  of  ihe  space,  ditto  6.3  dr.  5    ^^"^^    3  —    287    2    3 

XC.     Agrostis  mexicana.     Hort.     Kew,     I.  P.   150. 
Mexican  bent  grass.     Nat  of  S.  America. — 
Introduced  178  ,  by  M.  G.  Alexander. 
At  the  time'  of  flowering,  the  produce  from  a 

black  sandy  soil,  is 

Grass,  28  oz.    I'he  produce  per  acre  304920    0  — 19057    8    0 

80  dr.  of  grass  weigh  when  dry         28  dr..^ 

,         c.u  r./     i^Aoi^f    106722    0—6670   2     0 

The  produce  of  the  space,  ditto      156,3  loj  *     ^ 

The  weight  lost  by  the  produce  of  one  acre  Ln  drying  12387    6    0 

64  dr.  of  grass  afford  of  nutritive  matter  2  dv. ") 

The  produce  of  the  spce,  ditto  14  d   J  ^^^^    12  —  595     8    12 

XCI.     Stipa  pemiata,     Engl.     Bot.     1356.     Long- 
awned  feather  grass.     Nat.  of  Britain. 

At  the  time  of  flowering  the  produce  from  a  heath 
soil,  is 

Grass,  14    oz.    The  produce  per  acre  152460    0  —  9528    12    0 

80  dr.  of  grass  weigh  when  dry  29  dr.  >  ^^266 12  -  3454    2    12. 

The  produce  of  the  sptce,  ditto    81  1-5  drJ 

The  weight  lost  by  the  produce  of  one  acre  in  drying  6074    9    4 


''^^^""'l  65510-409  7  0 


Lxiv  APPEMJDlX. 

oz.        or  lbs.  per  acre 
64  dr.  of  grass  afford  of  nutritive  matter    •    2.3  dr. 
The  produce  t;f  thc'.^p^cr,  ditlo  9.2 

XCII.     Tnticwn  repens,     Engl.    Bot.     9>;9. 

Creeping  rooted  wheat  grass.     Nat.   of 
Britain. 
At  the  time  of  flowering,  the  produce  from  a  light 
clayey  loam,  is 

Grass,  18  (z.     Tiic  produce  per  {;cre  196020    0—12251    4    0 

80  dr.  ..fF:ra>s  weigh  when  dry  32  dr  )      78408  0-4900    8    0 

The  produce  of  the  space  (]itto  115  1-5  j 

The  weight  lost  by  ihe  pi-onuce  of  one  acre  in  dryin,^  7350  12    0 

64  dr.  of  grass  afford  of  nutritive  matter     2  dr.  ^  ^^^^^  ^q  __  „g,,  jo    jq 
The  produce  of  ihe  space  ditto  9  dr.  > 

64  dr.  of  the  roots,  afford  of  nutritive  matter  5.3  dr. 

The  proportional  value  of  the  roots,  is  therefore  to 

that  of  the  grass,  as  23  to  8. 

XCIII.     Alopecurus  agrestis.     Engl.     Bot.     848. 

A.  myosuroides.     Slender  fox-tail  grass. — 
Nat  of  Britain.     Curt.     Lond. 
At  the  time  of  flowering  the  produce  from   a 

light  sandy  loam  is 

Grass,  12  oz.    The  pioduce  per  acre  130680    0  —  8167    8    0 

80  dr.  of  grass  Weigh  when  dry  ^^'^^  l    5063S    8—3164    14    8 

The  produce  of  the  space  ditto  74.  1.  3-5  dr.  ) 

€4  d'.  of  '.  rass  afford  of  nutritive  matter     1.3  dr.  p  ^^^ 

„  ,  ,.  ^  *  ^     c  '^^^'^  4  —  223  5    4 

The  'produce  of  the  space  ditto  5.1  dr,  3 

XCIV.     Bro7?2us  asper.  Engl  Bot.   1172.  Curt. 

Lond.    Bromus  hirsutus.     Huds.   Bromus 

ramosus.  B.  sylvaticus,    volger.  B.  altissi- 

~    mus.  Hairy  stalked  brome  grass.  Nat.    of 

Britain. 

At  the  time  of  flowering,  the  produce  from  a  light 

sandy  soil,  is 

Grass,  20  oz.  The  produce  per  acre  217800  0  —  13612    8    0 


APPENDIX.  Lxv 

80  dr.  of  grass  weigh  when  dry  24  dr.-^ 

The  produce  of  the  space,  ditto  96  dr. 5  ^^^^^     0  —  4083  12    0 

The  weigiit  lost  by  the  produce  of  one  acre  in  drying  9528  12    0 

64  dr.  of  grass  afford  of  nutritive  matter     2  dr.  7 

The  J  rodiic,  of  the  space,  ditto  10  dr..)  ^^'^^     4  —  425    6    4 

XCV.  Phalaris  canariensis^  Engl.  Bot.  1310. 
Common  canary  grass.  Nat.  of  Britain. 
At  the  time  of  flowering,  the  produce  from  a  clay- 
ey loam,  is 

Grais,  80  oz.  The  produce  per  acre  871200  0  —  54450  0    0 

80  dr.  of  grass  weigh  when  dry  26  dr.-^ 

The  produce  ofthe  space,  ditto        416  di-.j   ^^^^^^    8—17697  9    8 

The  produce  in  weight  lost  by  drying        -        -        -         36752    6    6 

64  dr.  of  grafts  afford  of  nutritive  matter  1.2  dr. ") 

The  p  od.ce  of  ,.he  space,  ditto  30  dr./  20418  12  -1876   2  12 

XCVI.  Melica  cczrulea.  Curt.  Lond.  Engl.  Bot.  750 
Purple  melic  grass.  Nat.  of  Britain. 
At  the  time  of  flowering,  the  produce  from  a  light 
sandy  soil,  is 

Grass,  11  oz.    The  produce  per  acre 

80  dr.  of  grass  weigh  when  dry  30  dr.-> 

The  produce  of  the  space,  ditto  66  dr.  3 

The  weight  lost  by  the  produce  of  one  acre  in  drying 

64  dr.  of  grass  afford  of  nutritive  matter  1.2  dr.  ^ 

The  produce  of  ihe  space,  ditto  4.0  2-4  S    ^^^^    8  —     172    4    8 

XCVII.  Dactylis  cynosuroides,  Linn.  fil.  fasci.  1,  P.  17. 

American   cock's  foot  grass.     Nat.    of  N. 

America. 
At  the  time  of  flowering,  the  produce  from  a  clayey 
loam,  is 

Grass,  102    oz.    The  produce  per  acre            111780    0  —  69423  1    0 

80  dr.  of  grass  weigh  when  dry            ^^dr.^ggg^gg  Q^^^g^^  ^    q 

The  produce  of  the  space,  ditto    979 1-5  dr.  3 

The  weight  lost  by  tlie  produce  of  one  acre  in  drying              27769  8    0 

64  dr.  of  grass  afford  of  nutritive  matter  1.3  dr.  7 

The  produce  of  the  space,  ditto           44,2  2.45^^^''"   0-1898  4 


oz. 

or 

lbs.  per  acre 

119790 

0- 

-7486 

14 

0 

44921 

4- 

■-  2807 

9 

4 

Irying 

4679 

4 

2 

hX\l 


APPENDIX. 


Of  the  Time  intthich  different  Grasses  pro-^ 
(luce  Flowers  and  Seeds, 

To  decide  positively  the  exact  period  or  season, 
when  a  grass  always  comes  into  flower,  and  perfects 
its  seed,  will  be  found  impracticable;  for  a  variety  of 
circumstances  interfere.  Each  species  seems  to  pos- 
sess a  peculiar  life  in  which  various  periods  may  be 
distinctly  marked,  according  to  the  varieties  of  its  age, 
of  the  seasons,  soils,  exposures,  and  mode  of  culture. 

The  following  Table,  which  shews  the  time  of 
flowering,  and  the  time  of  ripening  the  seed  of  those 
grasses  growing  at  Woburn,  which  are  mentioned  in 
the  Experiments,  must,  therefore,  only  be  considered 
as  serving  for  a  test  of  comparison,  for  the  different 
grasses,  growing  under  the  same  circumstances. 


Time 

of           1 

Time  of  ripening 

Names. 

flowering. 

the  seed. 

Anihoxanthum  odoratum 

April 

29 

June 

21 

TIolcus  odoratus 

April 

29 

June 

25 

Cynosurus  caeruleus 

April 

30 

June 

20 

Alopecurus  pratensis 

May 

20 

June 

24 

A!opecuru8  alp'mus 

May 

20 

June 

34 

Poa  alpiiia 

May 

30 

June 

30 

Poa  pratensia 

May 

30 

July 

14 

Toa  caralea 

May 

30 

July 

14 

Avena  pubescens 

June 

13 

July 

8 

Festuca  Hordlformis 

June 

13 

July 

10 

Poa  trivial  is 

June 

13 

July 

10 

Festuca  glauca 

June 

13 

July 

10 

I'estuca  glabra 

June 

16 

July 

10 

Festuca  rubra 

June 

20 

July 

10 

Festuca  ovina 

June 

24 

July 

10 

Briza  niedi^ 

June 

24 

July 

10 

Dactylis  glomerata 

June 

24 

July 

14 

Bromus  tectorura 

June 

24 

July 

15 

restucacanibiica 

JuRe 

28 

July 

15 

Oromus  diandrus 

June 

28 

July 

16 

Vox  angustifoUa 

June 

28 

July 

15 

Avena  elatior 

June 

28 

July 

l« 

VoA  elatior 

June 

28 

July 

16 

Festuca  duriuscula 

July 

1 

July 

20 

Milium  effusum 

July 

1 

July 

20 

Festuca  pratensis 

July 

1 

July 

20 

Lolium  (-erenne 

July 

1 

July 

20 

APPENDIX. 


Lxvri 


Names. 


Cynosurus  cristatus 
Avena  pruensis 
Bromus  multiflorui 
Festaca  loliacea 
Poa  cristuta 
Festuca  myurus 
Aira  flexiiosa 
Hordeuin  bulbosum 
Festuca  calamaria 
Bromus  littoreus 
Festuca  elatior 
Xardus  stricta 
Triticum,  (species  of) 
Festuca  Fluitans 
Festuca  dumetorum 
Holcus  lanatus 
Poa  fertilis 
Arundo  colorata 
Poa  (species  of) 
Cynosurus  erucseformi* 
Phleum  nodosum 
Phleuni  pratense 
Klymus  arenariut 
KJymus  geniculatu* 
Trit'oILuin  pratense 
Trifolimn  macrorhizum 
Sanguisorba  canadensis 
Buiiirts  orientalis 
Medicago  sariva 
Hedysarum  onobrychU 
Hordeum  pratense 
Poa  conipresva 
Poa  aquatica 
Bromus  cristatus 
Elymus  sibircus. 
Air.i  caspitosa 
AverjH  flavescens 
Bromus  stcrilis 
Holcus  mollis 
Bromus  inermis 
Agrostis  vulgaris 
Agrostis  palusirif 
Panicum  dactylon 
Agrostis  stolonifera 
Agrost  s  stolonifera  (var.) 
Agrostis  canina 
Agrostis  stricta 
Festjca  pennata 
Panicum  viride 
Pauicum  sanguinale 
Agrostis  lobata 
Agrostis  repens 
Agrostis  fascicularit 
Agrostis  nivea 
Triticura  repens 
Alopecurus  agrettis 
Bromus  asper 
Agrostis  mexicona 


Timt 

;of 

Time  of 

ripening 

lowering. 

the  bed 

July 

6 

July 

28 

July 

ft 

July 

20 

July 

6 

July 

28 

July 

I 

July 

28 

July 

4 

July 

28 

July 

-     « 

July 

28 

July 

6 

July 

28 

July 

10 

July 

28 

July 

10 

July 

28 

July 

12 

Aug. 

6 

July 

12 

Aug. 

6 

July 

12 

Aug. 

6 

July 

12 

Aug 

10 

July 

14 

Aug. 

13 

July 

14 

July 

20 

July 

14 

July 

26 

July 

14 

July 

28 

July 

Id 

July 

28 

July 

10 

July 

30 

July 

16 

July 

30 

July 

16 

July 

30 

July 

16 

Jnly 

30 

July 

15 

July 

30 

July 

18 

July 

30 

July 

18 

July 

30 

July 

18 

July 

30 

July 

13 

July 

30 

July 

18 

July 

30 

July 

18 

Aug. 

6 

July 

18 

Aug. 

• 

July 

20 

Aug. 

8 

July 

20 

Aug. 

n 

July 

20 

Aug. 

• 

July 

24 

Aug. 

10 

July 

24 

Aug. 

10 

July 

24 

Aug. 

10 

July 

24 

Aug. 

li 

July 

24 

Aug. 

20 

July 

^4 

Aug. 

20 

July 

24 

Aug. 

20 

July 

34 

Aug. 

20 

July 

28 

Aug. 

28 

July 

28 

Aug. 

28 

July 

28 

Ang. 

3S 

July 

28 

Aug. 

28 

July 

28 

Aug. 

28 

July 

28 

Aug. 

30 

July 

28 

Aug, 

30 

Aug. 

S 

Aug. 

If 

Aug. 

6 

Aug. 

20 

Aug. 

6 

Aug. 

20 

Aug. 

8 

Aug. 

25 

Aug. 

10 

Aug. 

30 

Aug. 

10 

Aug. 

30 

Aug. 

10 

Aug. 

30 

Aug. 

10 

Sept. 

• 

Aug. 

10 

Sept. 

10 

Aug. 

15 

Sept. 

25 

LXVIII 

APPENDIX. 

Names. 

Time  of 
flowering. 

Time  of  ripening 
the  Seed. 

Stipa  pennata 
Melica  caerule* 
rhalaris  cananiensis 
Dactylis  cynosuroides* 

Aug.     15 
Aug.     20 
Aug.     30 
Aug,     30 

Sept.     25 
Sept.     30 
Sept.     30 
Oct.       20 

Of  the  different  Soils  referred  to  in  the 
Appendix . 

In  books  on  agriculture  and  gardening  much  un- 
certainty and  confusion  arises  from  the  want  of  regu-' 
lar  definitions  of  the  various  soils,  to  distinquish  them 
specifically  by  the  names  generally  used;  thus  the  term 
bog-earth,  is  almost  constantly  confounded  with  peat- 
moss, and  heath-soil;  also  the  term  '  light  loam,' 
*  heavy  soil,'  &c.  are  given  without  distinguishing  whe- 
ther that  be  '  light'  from  sand,  or  this  *  heavy'  from 
clay.  In  minute  experiments,  it  is  doubtless  of  con- 
sequence to  be  as  explicit  as  possible  in  those  parti- 
culars. The  following  short  descriptions  of  such 
soils  as  are  mentioned  in  the  details  of  the  experiment 
are  here  given  for  the  above  purpose. 

1st.  By  '  loam'  is  meant  any  of  the  earths  com- 
bined with  decayed  animal,  or  vegetable  matter. 

2nd.  '  Clayey-loam'  when  the  greatest  propor- 
tion is  clay. 

3rd.  *  Sandy- loam'  when  the  greatest  proportion 
is  sand. 


*  In  the  experiments  made  on  the  guantity  of  nutritive  matter  in  the  grasses, 
tut  at  the  time  the  seed  Was  ripe,  the  seeds  were  always  separated:  and  the  calcja- 
lations  for  nutritive  matter,  as  is  evident  from  the  details,  made  for  grass  and 
not  hay. 


APPENDIX.  Lxix 

4th.  *  Brown-loam*  when  the  greatest  propor- 
tion consists  of  decayed  vegetable  matter. 

5th.  '  Rich  black  loam'  when  sand,  clay,  ani- 
mal  and  vegetable  matters  are  combined  in  unequal 
proportions,  the  clay  greatly  divided,  being  in  the  least 
proportion,  and  the  sand  and  vegetable  matter  in  the 
greatest. 

The  Terms  '  light  sandy  soil,'  '  light  brown 
loam/  &c.  are  varieties  of  the  above,  as  expressed. 


Lxx  APPENDIX. 

Observations  on  the  chemical  Composition  of 
the  natriiive  matter  afforded  by  the  gras- 
ses in  their  different  States,  By  the  Edi- 
tor. 

I  have  made  experiments  on  most  of  the  soluble 
products  supposed  to  contain  the  nutritive  matter  of 
the  grasses,  i)btained  by  Mr.  Sinclair;  and  I  have  an- 
alysed a  few  of  them.  Minute  details  on  this  subject 
would  be  little  interesting  to  the  agriculturist,  and 
would  occupy  a  considerable  space;  I  shall  therefore 
content  myself  with  mentioning  some  particular  facts, 
and  some  general  conclusions,  which  may  tend  to  elu- 
cidate the  inquiry  respecting  the  fitness  of  the  different 
grasses  for  permanent  pasture,  or  for  alternation  as 
green  crops  with  grain. 

The  only  substances  which  I  have  detected  in  the 
soluble  matters  procured  from  the  grasses,  are  mucil- 
age, sugar,  bitter  extract,  a  substance  analogous  to 
albumen,  and  different  saline  matters.  Some  of  the 
products  from  the  after-math  crops  gave  feeble  indica- 
tions of  the  tanning  principle. 

The  order  in  which  these  are  nutritive  has  been 
mentioned  in  the  First  Lecture,  the  albumen,  sugar, 
and  mucilage,  probably  when  cattle  feed  on  grass  or 
hay,  are  for  the  most  part  retained  in  the  body  of  the 
animal;  and  the  bitter  principle,  extract,  saline  mat- 
ter, and  tannin,  when  any  exist,  probably  for  the  most 
part  are  voided  in  the  excrement,  with  the  woody 
fibre.  The  extractive  matter  obtained  by  boiling  the 
fresh  dung  of  cows,  is  extremely  similar  in  chemical 


APPENDIX.  hxxi 

characters  to  that  existing  in  the  soluble  products  from 
the  grasses.  And  some  extract,  obtained  by  Mr.  Sin- 
clair, from  the  dung  of  sheep  and  of  deer,  which  had 
been  feeding  upon  the  Lolium  perenne,  Dactylis  glom- 
erata,  and  Trifolium  repens,  had  qualities  so  anala- 
gous  to  those  of  the  extractive  matters  obtained  from 
the  leaves  of  the  grasses,  that  they  might  be  mistaken 
for  each  other.  The  extract  of  the  dung,  after  being 
kept  for  some  weeks,  had  still  the  odour  of  hay.  Sus- 
pecting that  some  undigested  grass  might  have  remain- 
ed in  the  dung,  which  might  have  furnished  mucilage 
and  sugar,  as  well  as  bitter  extract,  I  examined  the 
soluble  matter  very  carefully  for  these  substances.  It 
did  not  yield  an  atom  of  sugar,  and  scarcely  a  sensible 
quantity  of  mucilage. 

Mr.  Sinclair,  in  comparing  the  quantities  of  solu- 
ble matter  afforded  by  the  mixed  leaves  of  the  Lolium 
perenne,  Dactylis  glomerata,  and  Trifolium  repens, 
and  that  obtained  from  the  dung  of  cattle  fed  upon 
them,  found  their  relative  proportions  as  50  to  13. 

It  appears  probable  from  these  facts,  that  the  bit« 
ier  extract,  though  soluble  in  a  large  quantity  of  wa- 
ter, is  very  little  nutritive;  but  probably  it  serves  the 
purpose  of  preventing,  to  a  certain  extent,  the  fermen- 
tation of  the  other  vegetable  matters,  or  in  modifying 
or  assisting  the  function  of  digestion,  and  may  thus 
be  of  considerable  use  in  forming  a  constituent  part 
of  the  food  of  cattle.  A  small  quantity  of  bitter 
extract  and  saline  matter  is  probably  all  that  is  needed, 
and  beyond  this  quantity  the  soluble  matters  must  be 
more  nutritive  in  proportion  as  they  contain  more  al- 


Lxxii  APPENDIX. 

bumen,  sugar,  and  mucilage,  and  less  nutritive  in  pro- 
portion, as  they  contain  other  substances. 

In  comparing  the  composition  of  the  soluble  pro- 
ducts afforded  by  different  crops  from  the  same  grass, 
I  found,  in  all  the  trials  I  made,  the  largest  quantity 
of  truly  nutritive  matter,  in  the  crop  cut  when  the  seed 
was  ripe,  and  least  bitter  extract  and  saline  matter; 
most  extract  and  saline  matter  in  the  autumnal  cropj 
and  most  saccharine  matter,  in  proportion  to  the  other 
ingredients .  in  the  crop  cut  at  the  time  of  flowering. 
I  shall  give  one  instance: 

lOO  parts  of  the  soluble  matter  obtained  from 
the  Dactylis  glomerata,  cut  in  flower,  afforded 
of  sugar         -         -         -         -         18  parts 
of  mucilage  -         -         -         67 

of  coloured  extract,  and  saline  matters, 
with  some  matter  rendered  insoluble  by 
evaporation  -         -        -         15 

100  parts  of  the  soluble  matter  from  the 
seed  crop  afforded 

Sugar 9  parts 

Mucilage  ,         -         -         -      85 

Extract,  insoluble,  and  saline  matter     6 
100  parts  of  soluble  matter  from  the  after-math 
crop  give 

of  sugar         -        -         -         -  11  parts 

of  mucilage  ...  59 

of  extract,  insoluble,  and  saline  matters  30 
The  greater  proportion  of  leaves  in  the  spring, 
and  particularly  in  the  late  autumnal  crop,  accounts 
for  the  difference  in  the  quantity  of  extract;  and  the 


APPENDIX.  Lxxiii 

inferiority  of  the  comparative  quantity  of  sugar  in  the 
summer  crop,  probably  depends  upon  the  agency  of 
light,  which  tends  always  in  plants  to  convert  sacchar- 
ine matter  into  mucilage  or  starch. 

Amongst  the  soluble  matters  afforded  by  the 
different  grasses,  that  of  the  Elymus  arenarius  was  re- 
markable for  the  quantity  of  saccharine  matter  it  con- 
tained, amounting  to  more  than  one  third  of  its  weight. 
The  soluble  matters  from  the  different  species  of  Fes- 
tuca,  in  general  afford  more  bitter  extractive  matter 
than  those  from  the  different  species  of  Poa.  The 
nutritive  matter  from  the  seed  crop  of  the  Poa  com- 
pressa  was  almost  pure  mucilage.  The  soluble  mat- 
ter of  the  seed  crop  of  Phleum  pratense,  or  meadow 
cat's-tail,  afforded  more  sugar  than  any  of  the  Poa  or 
Festuca  species. 

The  soluble  parts  of  the  seed  crop  of  the  Holcus 
mollis  and  Holcus  lanatus  contained  no  bitter  extract, 
and  consisted  entirely  of  mucilage  and  sugar.  Those 
of  the  Holcus  odoratus  afforded  bitter  extract,  and  a 
peculiar  substance  having  an  acrid  taste,  more  soluble 
in  alcohol  than  in  water.  All  the  soluble  extracts  of 
those  grasses  that  are  most  liked  by  cattle,  have  either 
a  saline  or  subacid  taste  5  that  of  the  Holcus  lanatus, 
is  similar  in  taste  to  gum  arabic.  Probably  the  Holcus 
lanatus  which  is  so  common  a  grass  in  meadows,  might 
be  made  palatable  to  cattle  by  being  sprinkled  over 
with  salt. 

I  have  found  no  differences  in  the  nutritive  pro^ 
duce  of  the  crops  of  the  different  grasses  cut  at  the  same 
season,  which  would  render  it  possible  to  establish  a 

K 


L\xi7  APPENDIX. 

scale  of  their  nutritive  powers  j  but  probably  the  soluble 
matters  of  the  after-math  crop  are  always  from  one  sixth 
to  one  third  less  nutritive  than  those  from  the  flower 
or  seed  crop.  In  the  after-math  the  extractive  and 
saline  matters  are  certainly  usually  in  excess;  but  the 
after-math  hay  mixed  with  summer  hay,  particularly 
that  in  which  the  fox-tail  and  soft  grasses  are  abun- 
dant, would  procure  an  excellent  food. 

Of  the  clovers,  the  soluble  matter  from  the 
Dutch  clover  contains  most  mucilage,  and  most  matter 
analogous  to  albumen:  all  the  clovers  contain  more  bit- 
ter extract  and  saline  matter  than  the  common  proper 
grasses.  When  pure  clover  is  to  be  mixed  as  fodder, 
it  should  be  with  summer  hay,  rather  than  after-math 
hay* 


INDEX. 


Acids,  account  of  those  found 
in  vegetables,  96. 

Age  of  trees,  by  what  limited, 
225. 

Alcohol,  theory  of  its  forma- 
tion, 119. 

Alburnum,  uses  of,  54,  225. 

Alkalies,  method  of  ascertain- 
ing their  presence  in  plants, 
99. 

effects    produced   by,   in 
vegetation,  17 

Animal  substances,  their  com- 
position, &c.  245. 

—decomposition  of,  244. 

Atmosphere,  nature  and  con- 
stitution of,  183. 

Animal  matter,  mode  of  ascer- 
taining its  existence  in  soils, 
148. 

Bark,  its  office  and  uses,  51, 

211. 
Barks,  their  relative  value  for 

tanning  skin,  8  i . 
Blight  in  corn,  its  cause,  236. 
Bread,  its  manufacture,  theory 

of  its  production,  123. 
Burning,  its  use  in  improving 

soils,  309. 

Canker  in  trees,  probable  mode 
of  curing,  234. 

Carbonic  acid,  a  part  of  the  at- 
mosphere, 186, 

—necessary  to  vegetation, 
197. 


Cements,    on  those    obtained 

from  limestone,  290. 
Chemistry,  its  application  to 

agriculture,  5. 
importance  in  ag- 
ricultural pursuits,  23. 
Combustibles,  simple,  referred 

to,  40. 
Combustion,     supporters    of, 

mentioned  39. 
Courses  of  crops,    particular 

ones  recommended,  319. 
Corn,  its  tillering,  theory  of 

this  operation,  207. 

Diseases  of  Plants,  their  causes 
discussed,  233. 

Earths,  on  those  found  in 
plants,  101. 

Electricity,  its  influence  on  ve- 
getation, 37. 

Elements  chemical,  of  bodies, 
40. 

laws  of  their  com- 


binations, 46. 
Excrements,  use  of  as  ma- 
nures, 261. 

Fairy  rings,  their  causes,  319. 
Fallowing,  theory  of,  21,315. 
Fermentation,  phenomena  of, 

118. 
Fly-turnip,  plan  for  destroying 

or  preventing,  195. 
Flowers,  their  parts  and  office^ 

61, 


INDEX. 


Geology,  referred  to  as  teach- 
inj^  the  nature  of  rocks,  170» 

Grafting,  general  views  on  tliis 
process,  226. 

Grasses,  on  those  fit  for  pas- 
ture, 322. 

Gravitation,  its  effects  on 
plants,  29. 

Green  crops  recommended, 
317. 

Gypsum,  its  use  as  a  manure, 
293. 

Heat,  its  effects  on  vegetables, 
34,  158. 

Husbandry  drill,  its  advan- 
tages, 317. 

Ice,  its  anti-putrescent  pow- 
ers, 248. 

Irrigation,  theory  of  its  effects, 
313. 

Irritability,  vegetable,  its  exis- 
tence doubted,  216. 

Land,    causes  of  its  fertility, 

179. 

barrenness    180. 

Leaves,  their  functions,  58. 
Light,  its  effect  on  vegetation, 

197, 
Limestone,  its  nature  and  uses, 

19,281. 

' action  in  the  «oil,  19. 

— ■ mode    of  burning, 

293. 
magnesian,  its  peculiar 

properties,  2!,  287. 
Lime,    mode    of  ascertaining 

the  quantity  in  limestones 

and  soils,  147. 
~ —  salts  of,  on  the  mode  of 

detecting  them  in  soils,  152, 

Manures  on  their  applications, 
239. 

■ how  taken  into  the  ve- 
getable system,  240. 


Manures,  fermentation  of,  6, 

269. 
in    what    state    to  Wc 

used,  ';69. 

animal,  261. 

mineral,  285. 

vegetable,  249. 

saline,  260,  279. 

Malting,  theory  of  the  process 

of,  192. 
Matter,  powers  of  discussed, 

28. 
Metals,  account  of,  42. 
INIetallic  oxides,  those   found 

in  plants.  104. 
Mildew,  caube  of,  236. 
Meat,  method  of  preserving  it, 

248. 

Oils,  fiiied,  their  nature  and 

production,  92. 
Oxygene,  its  presence  in  the 

atmosphere,  and  uses,    188. 
necessary  to  germina- 


tion, 179,206. 

Paring  and  burning,  theory  of 
their  operation,  309. 

Pasture,  where  advantageous, 
322. 

Plants, organization  of,  50,123. 

Plants,  parasitical,  described  as 
the  cause  of  disease  in  corn, 
234. 

Peat  mosses,  on  their  forma- 
tion, 169. 

on    their    improve- 


ment- 181. 

Putrefaction,  methods  of  pre- 
venting, 248. 

Pith,  nature  of,  56. 

Plants,  parts  of,  50. 

Quicklime,  injurious  to  soils, 

283, 

Rocks,  their  number  and  ar- 
rangement, 171. 


INDEX. 


Kocksj  those  from  which  soils 
are  derived,  or  oh  which 
they  rest,  175. 

Sap,  cause  of  its  ascent  discus- 
sed, 211. 
course  of  8,  209. 

—  its  composition  discus- 
sed, 131. 

Salts  their  uses  as    manure, 

261,279. 
■         on  such  as  are  found  in 

vegetables,  102. 
on  those  found  in  soils, 

account  of,   139. 
Seeds,  on  those  produced  by 

crossing,  229. 

germination  of,  1 89. 

their  nature  and  uses,  63. 

Simple  substances  described, 

40. 
Soils,  properties  of,  157,   142. 
composition  of,  136,  154. 

—  method  of  analysing,  140. 

formation  of,    <66. 

their    constituent  parts, 

136. 

improvement  of,  181. 

their  classification,  178. 

Subsoils,  varieties  of,  and  their 
effects,  166. 

Soot,  properties  of  as  a  ma- 
nure, 274. 

Sugar,  mode  of  refining,  71, 

Tanning  principle,  its  applica- 
tion to  tanning,  79. 

— quantity  in  differ- 
ent barks,  80. 

artificial,  83. 


Temperature  of  soils  discus- 
sed, 158. 

Trees,  habits  of,  discussed, 
232. 

cause  of  their  decay, 

225. 


Trees,  age  of,  226. 

Urine,  its  use  as  a  manure, 

261. 

Vegetables,    their     chemical 
composition,  67. 

improvement  of, by  cul- 


tivation, 228. 

renovation  of  the  at- 


mosphere, 203. 

the    causes    of    their 


growth  discussed,  220. 

Vegetable  matter,  mode  of  as- 
certaining its  quantity  in 
soils,  148. 

its  analysis,  107. 

decomposition     of, 


described,  244. 

principles,    their    ar- 


rangement in  plants,  123. 
Vegetable  life,  phasnomena  of, 
discussed,  219. 

matter,  decomposition 


of,  242. 

Vegetation,  influenced  by  gra- 
vitation, 29. 

influence  of  light  in, 


208. 


302. 


progress    of,    195, 
its  effect  on  a  soil, 


18. 


Veins  or  mines,  their  situa- 
tions, 174. 

Water,  absorption  of  by  soils, 
161. 

its  state  in  the  atmos- 
phere, 186 

Wheat,  transplantation  of,  208. 

crossing  of,  228. 

Wines,  theory  of  their  forma- 
tion, 119. 

~ quantity  of  spirits  they 

contain,  121. 


INDEX  TO  THE  APPENDIX. 


Jgrostia  canina^  brown  bent, 

lix. 
canma     var,     mutica) 

awnless  brown  bent,  Ix. 

fascicularisj  tufted-lea- 


ved bent,  Ixi. 

i.bata^     lobcd      bent 


grass,  Ixii. 
mexicanay 


mexican 


bent  grass,  Ixiii. 

niveciy     snowy      bent 


grass,  Ixvi. 

Jialustrisy  March  bent 


grass,  Ivii. 
re/iens,  creeping  root- 
ed bent,  Ixiii.  ^ 

s'ricta,   upright    bent 


grass?  Ix. 

ii.  stolonJfcra,  fjorin  creep- 


ing bent,  Iviii. 

stolonlfera  var.  an^us- 


tifolla^  creeping  bent  narrow 
leaves,  lix. 

vulgaris^      fine     bent 


grass,  Ivi 
AL7-a  aquatica,  water  hair  grass, 

xlvii. 
c^es/ntosa,  turfy  hair  grass 

xlviii. 
— — JlexuosUy  waved   moun- 
tain hair  grass,  xxxv. 
Mojiecurus    agrusth;    slender 

fox-tail  grass,  Ixiv. 
' aljiinus,  alpine  fox 

tail  grass,  x. 
. . /t7'a;^ns/*,  meadow 

fox- tail  grass,  viii. 
A  iihoxanthum  odoratum^ sweet 

scented  vernal  grass,  v. 
Arimd:'  colorataf  striped-leaved 

reed  grass,  xli. 
Avena  e-aiior,  tall   oat  grass, 

XXV. 


Jlavescensy  yellow  oat 

grass,  xlix. 

firatensisy  meadow  oat 


grass,  xxxu. 

fiubescens^  downy  oat 

grass,  X. 

Briza  mediay    quaking  grass, 

XX. 

Brojuus  asfier^  Ixiv. 

cristatua^  xlvii. 

diandruy  xxiii. 

erectusf  upright  peren- 
nial brome  grass,  xxvii. 

inernisy  awniess  brome 


grass,  Iv. 

Uttoreusi      sea      side 


brome  grass,  xxxvii. 

multijiorusy      many 


flowering  bronxe  grass,  xxxii. 
tectorum^  nodding  pan- 


nicled  brome  grass,  xxii. 

stcriiisy  barren  brome 

grass,  1. 
Bunias  orientalise  xlii. 

Cynosurus  c<eruleuSf  blue  moor 

gras^,  vii. 
Cynosurus    cristatus,     crested 

dog's-tail  grass,  xxxi. 
— . erucxformisy     linear 

spiked  dog's-tail  grass,  lii. 

Dactylis  cynosuroidesy  Ameri- 
can cock's  foot  grass,  Ixv. 

glotnerata,  round-head- 
ed cock's  foot  grass,  xxi. 

Elymus  arenarius,  upright  sea 

lyme  grass,  Iv. 
geniculatusy  pendulous 

sea  lyme  grass,  Iv.    • 


INDEX. 


Jilymus     sibericusf     Siberian 
lyme  grass,  xlviii. 

Festuca    ca/amaria,    reed-like 

fescue  grass,  xxxv. 
•  cambrica^  xxii. 
duriuscula^  hard  fescue 

grass,  xxvi. 

duDieiorwri)  pubescent 


fescue  grass,  xl. 

e iatior yimW  fescue  grass 


XXXVlll. 

— —  Jluitansi   floating  fes- 
cue grass,  xxxix. 

glabra^  smooth  fescue 

grass,  xvi. 

glauca^  glaucares  fes- 
cue grass,  XV. 

/i or dif or ?nis ^barley  like 

fescue  grass,  xiii. 
loliacea,  spiked  fescue 


wall    fescue 


grass,  xxxui. 

myurus, 

grass,  xxxiv. 

o-uway  sheeps*  fescue 


grass,  XIX. 

ficnnatay  spiked  fescue 


grass,  Ixi, 

:  firatensis^  meadow  fes- 


cue grass,  xxviii. 

. — rubra,    purple  fescue 

grass,  xviii. 

Hedyaarum    onobrychisy   sain- 
foin, xlv. 

Hordeujn    bulbosuniy     bulbous 
barley  grass,  xxxv. 

marinuTTif  wall  barley 

grass,  xlviii. 

firatensey  meadow  bar- 


ley grass,  xlvi. 
Holcus  lanatus,  meadow  soft 
grass,  xl. 

—  mollisy    creeping   soft 
grass,  1. 

odoratus,  sweet-scent- 


ed  soft  grass,  yi. 


Lolium  fierenney  perennial  rye 
grass,  xxix. 

Medicago  safivOy  lucerne,  xlv. 

Melica  caruleuy  purple  malic 
grass,  Ixv. 

Milium  effuswny  common  mil- 
let grass,  xxviii. 

Mirdum  strictay  upright  mat 
grass,  xxxix. 


creepmg 


Panicum    dactylony 
panic  grass,  Iviii. 

sanguinale,    blood-co- 


loured panic  grass,  Ixii. 

viridey     green     panic 


grass,  Ixi. 

Phalaris  cananiensis,  common 
canary  grass,  Ixv. 

Pltleum  nodosum,  bulbous- 
stalked  cat*s-tail  grass,  Hi. 

jiratense,      meadow 


cat's-tail  grass,  liii. 

var^    minor^    meadow 


cat*s-tail  grass,  var»  smaller, 
liv. 

Poa  alfiinay  alpine  meadow- 
grass,  X. 

— — —  angustifoliay  narrow- 
leaved  meadow  grass  xxiii.' 

aquaticQy  reed  meadow 

grass,  xlvii. 

caruleuy  v.fi.  firatense. 

short  bluish  meadow  grass, 
xiii. 

comfir essay  flat-stalked 

meadow  grass,  xlvi. 

cristata,  crested  mea- 


dow grass,  xxxiv. 
datiory    tall    m^eadow 

grass,  xxvi. 
— fertilisy  fertile  meadow 

grass,  xli. 
x,cr,  6.    fertile 

meadow  grass,  var.  I,  li. 

maritima^  sea  meadow 

grass,  XXX, 


INDEX. 


Poa     firaiensisi  smooth- 

stalked  meadow  grass,  xii. 

trivialisy  roughish  mea- 
dow grass,  xiv. 

Fotirimn  sanguisorba,  burnet, 
xxxvii. 

Stifia  fiennatQy  long  armed  fea- 
ther grass,  Ixiii. 


Trifolium  macrorhizum^  long 
rooted  clover,  xxxviii. 

firatenscy  broad  lea- 
ved cultivated  clover,  xlii. 

refiensy  white  clover, 

Ixiii. 

Triticum  refiens^  creeping  root- 
ed wheat  grass,  Ixiv. 

sfi^    wheat    grass, 


xxxix. 


FINr 


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